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* [syzbot] net-next boot error: WARNING: refcount bug in fib_create_info
@ 2021-08-03 16:07 syzbot
  2021-08-03 16:12 ` Pavel Skripkin
  0 siblings, 1 reply; 6+ messages in thread
From: syzbot @ 2021-08-03 16:07 UTC (permalink / raw)
  To: davem, dsahern, kuba, linux-kernel, netdev, syzkaller-bugs, yoshfuji

Hello,

syzbot found the following issue on:

HEAD commit:    1187c8c4642d net: phy: mscc: make some arrays static const..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=140e7b3e300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f9bb42efdc6f1d7
dashboard link: https://syzkaller.appspot.com/bug?extid=c5ac86461673ef58847c
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c5ac86461673ef58847c@syzkaller.appspotmail.com

FS-Cache: Netfs 'afs' registered for caching
Btrfs loaded, crc32c=crc32c-intel, assert=on, zoned=yes
Key type big_key registered
Key type encrypted registered
AppArmor: AppArmor sha1 policy hashing enabled
ima: No TPM chip found, activating TPM-bypass!
Loading compiled-in module X.509 certificates
Loaded X.509 cert 'Build time autogenerated kernel key: f850c787ad998c396ae089c083b940ff0a9abb77'
ima: Allocated hash algorithm: sha256
ima: No architecture policies found
evm: Initialising EVM extended attributes:
evm: security.selinux (disabled)
evm: security.SMACK64 (disabled)
evm: security.SMACK64EXEC (disabled)
evm: security.SMACK64TRANSMUTE (disabled)
evm: security.SMACK64MMAP (disabled)
evm: security.apparmor
evm: security.ima
evm: security.capability
evm: HMAC attrs: 0x1
PM:   Magic number: 1:990:690
printk: console [netcon0] enabled
netconsole: network logging started
gtp: GTP module loaded (pdp ctx size 104 bytes)
rdma_rxe: loaded
cfg80211: Loading compiled-in X.509 certificates for regulatory database
cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
ALSA device list:
  #0: Dummy 1
  #1: Loopback 1
  #2: Virtual MIDI Card 1
md: Waiting for all devices to be available before autodetect
md: If you don't use raid, use raid=noautodetect
md: Autodetecting RAID arrays.
md: autorun ...
md: ... autorun DONE.
EXT4-fs (sda1): mounted filesystem without journal. Opts: (null). Quota mode: none.
VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
devtmpfs: mounted
Freeing unused kernel image (initmem) memory: 4476K
Write protecting the kernel read-only data: 169984k
Freeing unused kernel image (text/rodata gap) memory: 2012K
Freeing unused kernel image (rodata/data gap) memory: 1516K
Run /sbin/init as init process
systemd[1]: systemd 232 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN)
systemd[1]: Detected virtualization kvm.
systemd[1]: Detected architecture x86-64.
systemd[1]: Set hostname to <syzkaller>.
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Modules linked in:
CPU: 1 PID: 1 Comm: systemd Not tainted 5.14.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
Code: 09 31 ff 89 de e8 d7 fa 9e fd 84 db 0f 85 36 ff ff ff e8 8a f4 9e fd 48 c7 c7 c0 81 e3 89 c6 05 70 51 81 09 01 e8 48 f8 13 05 <0f> 0b e9 17 ff ff ff e8 6b f4 9e fd 0f b6 1d 55 51 81 09 31 ff 89
RSP: 0018:ffffc90000c66ab0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88813fe48000 RSI: ffffffff815d7b25 RDI: fffff5200018cd48
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff815d195e R11: 0000000000000000 R12: 0000000000000004
R13: 0000000000000001 R14: 0000000000000000 R15: ffff888027722e00
FS:  00007f8c1c5d0500(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055ed0ced4368 CR3: 0000000026bac000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __refcount_add include/linux/refcount.h:199 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 fib_create_info+0x36af/0x4910 net/ipv4/fib_semantics.c:1554
 fib_table_insert+0x1cd/0x1af0 net/ipv4/fib_trie.c:1224
 fib_magic+0x455/0x540 net/ipv4/fib_frontend.c:1087
 fib_add_ifaddr+0x16c/0x500 net/ipv4/fib_frontend.c:1109
 fib_inetaddr_event+0x162/0x2a0 net/ipv4/fib_frontend.c:1420
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 blocking_notifier_call_chain kernel/notifier.c:337 [inline]
 blocking_notifier_call_chain+0x67/0x90 kernel/notifier.c:325
 __inet_insert_ifa+0x919/0xc20 net/ipv4/devinet.c:553
 inet_insert_ifa net/ipv4/devinet.c:560 [inline]
 inetdev_event+0x1243/0x15d0 net/ipv4/devinet.c:1570
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2123
 call_netdevice_notifiers_extack net/core/dev.c:2135 [inline]
 call_netdevice_notifiers net/core/dev.c:2149 [inline]
 __dev_notify_flags+0x110/0x2b0 net/core/dev.c:8878
 dev_change_flags+0x112/0x170 net/core/dev.c:8916
 do_setlink+0x913/0x3910 net/core/rtnetlink.c:2710
 rtnl_setlink+0x24d/0x3c0 net/core/rtnetlink.c:3003
 rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5563
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:724
 __sys_sendto+0x21c/0x320 net/socket.c:2030
 __do_sys_sendto net/socket.c:2042 [inline]
 __se_sys_sendto net/socket.c:2038 [inline]
 __x64_sys_sendto+0xdd/0x1b0 net/socket.c:2038
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f8c1ae6d693
Code: 79 20 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb cd 66 0f 1f 44 00 00 83 3d 39 bd 20 00 00 75 13 49 89 ca b8 2c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 cb f7 ff ff 48 89 04 24
RSP: 002b:00007fffa5944aa8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000055ed0ceca9a0 RCX: 00007f8c1ae6d693
RDX: 0000000000000020 RSI: 000055ed0ceca2b0 RDI: 0000000000000004
RBP: 000055ed0cecaab0 R08: 00007fffa5944ab0 R09: 0000000000000010
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffa5944b14
R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000001


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] net-next boot error: WARNING: refcount bug in fib_create_info
  2021-08-03 16:07 [syzbot] net-next boot error: WARNING: refcount bug in fib_create_info syzbot
@ 2021-08-03 16:12 ` Pavel Skripkin
  2021-08-03 16:31   ` Pavel Skripkin
  0 siblings, 1 reply; 6+ messages in thread
From: Pavel Skripkin @ 2021-08-03 16:12 UTC (permalink / raw)
  To: syzbot, davem, dsahern, kuba, linux-kernel, netdev,
	syzkaller-bugs, yoshfuji

On 8/3/21 7:07 PM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    1187c8c4642d net: phy: mscc: make some arrays static const..
> git tree:       net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=140e7b3e300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f9bb42efdc6f1d7
> dashboard link: https://syzkaller.appspot.com/bug?extid=c5ac86461673ef58847c
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+c5ac86461673ef58847c@syzkaller.appspotmail.com
> 
> FS-Cache: Netfs 'afs' registered for caching
> Btrfs loaded, crc32c=crc32c-intel, assert=on, zoned=yes
> Key type big_key registered
> Key type encrypted registered
> AppArmor: AppArmor sha1 policy hashing enabled
> ima: No TPM chip found, activating TPM-bypass!
> Loading compiled-in module X.509 certificates
> Loaded X.509 cert 'Build time autogenerated kernel key: f850c787ad998c396ae089c083b940ff0a9abb77'
> ima: Allocated hash algorithm: sha256
> ima: No architecture policies found
> evm: Initialising EVM extended attributes:
> evm: security.selinux (disabled)
> evm: security.SMACK64 (disabled)
> evm: security.SMACK64EXEC (disabled)
> evm: security.SMACK64TRANSMUTE (disabled)
> evm: security.SMACK64MMAP (disabled)
> evm: security.apparmor
> evm: security.ima
> evm: security.capability
> evm: HMAC attrs: 0x1
> PM:   Magic number: 1:990:690
> printk: console [netcon0] enabled
> netconsole: network logging started
> gtp: GTP module loaded (pdp ctx size 104 bytes)
> rdma_rxe: loaded
> cfg80211: Loading compiled-in X.509 certificates for regulatory database
> cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
> ALSA device list:
>    #0: Dummy 1
>    #1: Loopback 1
>    #2: Virtual MIDI Card 1
> md: Waiting for all devices to be available before autodetect
> md: If you don't use raid, use raid=noautodetect
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: ... autorun DONE.
> EXT4-fs (sda1): mounted filesystem without journal. Opts: (null). Quota mode: none.
> VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
> devtmpfs: mounted
> Freeing unused kernel image (initmem) memory: 4476K
> Write protecting the kernel read-only data: 169984k
> Freeing unused kernel image (text/rodata gap) memory: 2012K
> Freeing unused kernel image (rodata/data gap) memory: 1516K
> Run /sbin/init as init process
> systemd[1]: systemd 232 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN)
> systemd[1]: Detected virtualization kvm.
> systemd[1]: Detected architecture x86-64.
> systemd[1]: Set hostname to <syzkaller>.
> ------------[ cut here ]------------
> refcount_t: addition on 0; use-after-free.
> WARNING: CPU: 1 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
> Modules linked in:
> CPU: 1 PID: 1 Comm: systemd Not tainted 5.14.0-rc3-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
> Code: 09 31 ff 89 de e8 d7 fa 9e fd 84 db 0f 85 36 ff ff ff e8 8a f4 9e fd 48 c7 c7 c0 81 e3 89 c6 05 70 51 81 09 01 e8 48 f8 13 05 <0f> 0b e9 17 ff ff ff e8 6b f4 9e fd 0f b6 1d 55 51 81 09 31 ff 89
> RSP: 0018:ffffc90000c66ab0 EFLAGS: 00010286
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: ffff88813fe48000 RSI: ffffffff815d7b25 RDI: fffff5200018cd48
> RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000001
> R10: ffffffff815d195e R11: 0000000000000000 R12: 0000000000000004
> R13: 0000000000000001 R14: 0000000000000000 R15: ffff888027722e00
> FS:  00007f8c1c5d0500(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055ed0ced4368 CR3: 0000000026bac000 CR4: 00000000001506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   __refcount_add include/linux/refcount.h:199 [inline]
>   __refcount_inc include/linux/refcount.h:250 [inline]
>   refcount_inc include/linux/refcount.h:267 [inline]
>   fib_create_info+0x36af/0x4910 net/ipv4/fib_semantics.c:1554

Missed refcount_set(), I think

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index f29feb7772da..bb9949f6bb70 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1428,6 +1428,7 @@ struct fib_info *fib_create_info(struct fib_config 
*cfg,
  	}

  	fib_info_cnt++;
+	refcount_set(&fi->fib_treeref, 1);
  	fi->fib_net = net;
  	fi->fib_protocol = cfg->fc_protocol;
  	fi->fib_scope = cfg->fc_scope;





With regards,
Pavel Skripkin

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] net-next boot error: WARNING: refcount bug in fib_create_info
  2021-08-03 16:12 ` Pavel Skripkin
@ 2021-08-03 16:31   ` Pavel Skripkin
  2021-08-03 21:04     ` Jakub Kicinski
  0 siblings, 1 reply; 6+ messages in thread
From: Pavel Skripkin @ 2021-08-03 16:31 UTC (permalink / raw)
  To: syzbot, davem, dsahern, kuba, linux-kernel, netdev,
	syzkaller-bugs, yoshfuji

On 8/3/21 7:12 PM, Pavel Skripkin wrote:
> On 8/3/21 7:07 PM, syzbot wrote:
>> Hello,
>> 
>> syzbot found the following issue on:
>> 
>> HEAD commit:    1187c8c4642d net: phy: mscc: make some arrays static const..
>> git tree:       net-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=140e7b3e300000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=f9bb42efdc6f1d7
>> dashboard link: https://syzkaller.appspot.com/bug?extid=c5ac86461673ef58847c
>> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
>> 
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+c5ac86461673ef58847c@syzkaller.appspotmail.com
>> 
>> FS-Cache: Netfs 'afs' registered for caching
>> Btrfs loaded, crc32c=crc32c-intel, assert=on, zoned=yes
>> Key type big_key registered
>> Key type encrypted registered
>> AppArmor: AppArmor sha1 policy hashing enabled
>> ima: No TPM chip found, activating TPM-bypass!
>> Loading compiled-in module X.509 certificates
>> Loaded X.509 cert 'Build time autogenerated kernel key: f850c787ad998c396ae089c083b940ff0a9abb77'
>> ima: Allocated hash algorithm: sha256
>> ima: No architecture policies found
>> evm: Initialising EVM extended attributes:
>> evm: security.selinux (disabled)
>> evm: security.SMACK64 (disabled)
>> evm: security.SMACK64EXEC (disabled)
>> evm: security.SMACK64TRANSMUTE (disabled)
>> evm: security.SMACK64MMAP (disabled)
>> evm: security.apparmor
>> evm: security.ima
>> evm: security.capability
>> evm: HMAC attrs: 0x1
>> PM:   Magic number: 1:990:690
>> printk: console [netcon0] enabled
>> netconsole: network logging started
>> gtp: GTP module loaded (pdp ctx size 104 bytes)
>> rdma_rxe: loaded
>> cfg80211: Loading compiled-in X.509 certificates for regulatory database
>> cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
>> ALSA device list:
>>    #0: Dummy 1
>>    #1: Loopback 1
>>    #2: Virtual MIDI Card 1
>> md: Waiting for all devices to be available before autodetect
>> md: If you don't use raid, use raid=noautodetect
>> md: Autodetecting RAID arrays.
>> md: autorun ...
>> md: ... autorun DONE.
>> EXT4-fs (sda1): mounted filesystem without journal. Opts: (null). Quota mode: none.
>> VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
>> devtmpfs: mounted
>> Freeing unused kernel image (initmem) memory: 4476K
>> Write protecting the kernel read-only data: 169984k
>> Freeing unused kernel image (text/rodata gap) memory: 2012K
>> Freeing unused kernel image (rodata/data gap) memory: 1516K
>> Run /sbin/init as init process
>> systemd[1]: systemd 232 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN)
>> systemd[1]: Detected virtualization kvm.
>> systemd[1]: Detected architecture x86-64.
>> systemd[1]: Set hostname to <syzkaller>.
>> ------------[ cut here ]------------
>> refcount_t: addition on 0; use-after-free.
>> WARNING: CPU: 1 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
>> Modules linked in:
>> CPU: 1 PID: 1 Comm: systemd Not tainted 5.14.0-rc3-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>> RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
>> Code: 09 31 ff 89 de e8 d7 fa 9e fd 84 db 0f 85 36 ff ff ff e8 8a f4 9e fd 48 c7 c7 c0 81 e3 89 c6 05 70 51 81 09 01 e8 48 f8 13 05 <0f> 0b e9 17 ff ff ff e8 6b f4 9e fd 0f b6 1d 55 51 81 09 31 ff 89
>> RSP: 0018:ffffc90000c66ab0 EFLAGS: 00010286
>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
>> RDX: ffff88813fe48000 RSI: ffffffff815d7b25 RDI: fffff5200018cd48
>> RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000001
>> R10: ffffffff815d195e R11: 0000000000000000 R12: 0000000000000004
>> R13: 0000000000000001 R14: 0000000000000000 R15: ffff888027722e00
>> FS:  00007f8c1c5d0500(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 000055ed0ced4368 CR3: 0000000026bac000 CR4: 00000000001506e0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>   __refcount_add include/linux/refcount.h:199 [inline]
>>   __refcount_inc include/linux/refcount.h:250 [inline]
>>   refcount_inc include/linux/refcount.h:267 [inline]
>>   fib_create_info+0x36af/0x4910 net/ipv4/fib_semantics.c:1554
> 
> Missed refcount_set(), I think
> 
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> index f29feb7772da..bb9949f6bb70 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -1428,6 +1428,7 @@ struct fib_info *fib_create_info(struct fib_config
> *cfg,
>    	}
> 
>    	fib_info_cnt++;
> +	refcount_set(&fi->fib_treeref, 1);
>    	fi->fib_net = net;
>    	fi->fib_protocol = cfg->fc_protocol;
>    	fi->fib_scope = cfg->fc_scope;
> 
> 
> 
> 
> 

Oops, it's already fixed in -next, so

#syz fix: ipv4: Fix refcount warning for new fib_info


BTW: there is one more bug with refcounts:

link_it:
	ofi = fib_find_info(fi);
	if (ofi) {
		fi->fib_dead = 1;
		free_fib_info(fi);
		refcount_inc(&ofi->fib_treeref);

		^^^^^^^^^^^^^^^^^^^^^^^
		/ *fib_treeref is 0 here */

		return ofi;
	}

	refcount_set(&fi->fib_treeref, 1);



diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index f29feb7772da..38d1fc4d0be1 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1543,6 +1543,8 @@ struct fib_info *fib_create_info(struct fib_config 
*cfg,
  	}

  link_it:
+	refcount_set(&fi->fib_treeref, 1);
+
  	ofi = fib_find_info(fi);
  	if (ofi) {
  		fi->fib_dead = 1;
@@ -1551,7 +1553,6 @@ struct fib_info *fib_create_info(struct fib_config 
*cfg,
  		return ofi;
  	}

-	refcount_set(&fi->fib_treeref, 1);
  	refcount_set(&fi->fib_clntref, 1);
  	spin_lock_bh(&fib_info_lock);
  	hlist_add_head(&fi->fib_hash,



Thoughts?


With regards,
Pavel Skripkin

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] net-next boot error: WARNING: refcount bug in fib_create_info
  2021-08-03 16:31   ` Pavel Skripkin
@ 2021-08-03 21:04     ` Jakub Kicinski
  2021-08-03 22:32       ` David Ahern
  2021-08-04  5:05       ` Pavel Skripkin
  0 siblings, 2 replies; 6+ messages in thread
From: Jakub Kicinski @ 2021-08-03 21:04 UTC (permalink / raw)
  To: Pavel Skripkin
  Cc: syzbot, davem, dsahern, linux-kernel, netdev, syzkaller-bugs, yoshfuji

On Tue, 3 Aug 2021 19:31:50 +0300 Pavel Skripkin wrote:
> On 8/3/21 7:12 PM, Pavel Skripkin wrote:
> > On 8/3/21 7:07 PM, syzbot wrote:  
> >> Hello,
> >> 
> >> syzbot found the following issue on:
> >> 
> >> HEAD commit:    1187c8c4642d net: phy: mscc: make some arrays static const..
> >> git tree:       net-next
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=140e7b3e300000
> >> kernel config:  https://syzkaller.appspot.com/x/.config?x=f9bb42efdc6f1d7
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=c5ac86461673ef58847c
> >> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
> >> 
> >> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> >> Reported-by: syzbot+c5ac86461673ef58847c@syzkaller.appspotmail.com
> >> 
> >> FS-Cache: Netfs 'afs' registered for caching
> >> Btrfs loaded, crc32c=crc32c-intel, assert=on, zoned=yes
> >> Key type big_key registered
> >> Key type encrypted registered
> >> AppArmor: AppArmor sha1 policy hashing enabled
> >> ima: No TPM chip found, activating TPM-bypass!
> >> Loading compiled-in module X.509 certificates
> >> Loaded X.509 cert 'Build time autogenerated kernel key: f850c787ad998c396ae089c083b940ff0a9abb77'
> >> ima: Allocated hash algorithm: sha256
> >> ima: No architecture policies found
> >> evm: Initialising EVM extended attributes:
> >> evm: security.selinux (disabled)
> >> evm: security.SMACK64 (disabled)
> >> evm: security.SMACK64EXEC (disabled)
> >> evm: security.SMACK64TRANSMUTE (disabled)
> >> evm: security.SMACK64MMAP (disabled)
> >> evm: security.apparmor
> >> evm: security.ima
> >> evm: security.capability
> >> evm: HMAC attrs: 0x1
> >> PM:   Magic number: 1:990:690
> >> printk: console [netcon0] enabled
> >> netconsole: network logging started
> >> gtp: GTP module loaded (pdp ctx size 104 bytes)
> >> rdma_rxe: loaded
> >> cfg80211: Loading compiled-in X.509 certificates for regulatory database
> >> cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
> >> ALSA device list:
> >>    #0: Dummy 1
> >>    #1: Loopback 1
> >>    #2: Virtual MIDI Card 1
> >> md: Waiting for all devices to be available before autodetect
> >> md: If you don't use raid, use raid=noautodetect
> >> md: Autodetecting RAID arrays.
> >> md: autorun ...
> >> md: ... autorun DONE.
> >> EXT4-fs (sda1): mounted filesystem without journal. Opts: (null). Quota mode: none.
> >> VFS: Mounted root (ext4 filesystem) readonly on device 8:1.
> >> devtmpfs: mounted
> >> Freeing unused kernel image (initmem) memory: 4476K
> >> Write protecting the kernel read-only data: 169984k
> >> Freeing unused kernel image (text/rodata gap) memory: 2012K
> >> Freeing unused kernel image (rodata/data gap) memory: 1516K
> >> Run /sbin/init as init process
> >> systemd[1]: systemd 232 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN)
> >> systemd[1]: Detected virtualization kvm.
> >> systemd[1]: Detected architecture x86-64.
> >> systemd[1]: Set hostname to <syzkaller>.
> >> ------------[ cut here ]------------
> >> refcount_t: addition on 0; use-after-free.
> >> WARNING: CPU: 1 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
> >> Modules linked in:
> >> CPU: 1 PID: 1 Comm: systemd Not tainted 5.14.0-rc3-syzkaller #0
> >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> >> RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
> >> Code: 09 31 ff 89 de e8 d7 fa 9e fd 84 db 0f 85 36 ff ff ff e8 8a f4 9e fd 48 c7 c7 c0 81 e3 89 c6 05 70 51 81 09 01 e8 48 f8 13 05 <0f> 0b e9 17 ff ff ff e8 6b f4 9e fd 0f b6 1d 55 51 81 09 31 ff 89
> >> RSP: 0018:ffffc90000c66ab0 EFLAGS: 00010286
> >> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> >> RDX: ffff88813fe48000 RSI: ffffffff815d7b25 RDI: fffff5200018cd48
> >> RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000001
> >> R10: ffffffff815d195e R11: 0000000000000000 R12: 0000000000000004
> >> R13: 0000000000000001 R14: 0000000000000000 R15: ffff888027722e00
> >> FS:  00007f8c1c5d0500(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> >> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >> CR2: 000055ed0ced4368 CR3: 0000000026bac000 CR4: 00000000001506e0
> >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> >> Call Trace:
> >>   __refcount_add include/linux/refcount.h:199 [inline]
> >>   __refcount_inc include/linux/refcount.h:250 [inline]
> >>   refcount_inc include/linux/refcount.h:267 [inline]
> >>   fib_create_info+0x36af/0x4910 net/ipv4/fib_semantics.c:1554  
> > 
> > Missed refcount_set(), I think
> > 
> > diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> > index f29feb7772da..bb9949f6bb70 100644
> > --- a/net/ipv4/fib_semantics.c
> > +++ b/net/ipv4/fib_semantics.c
> > @@ -1428,6 +1428,7 @@ struct fib_info *fib_create_info(struct fib_config
> > *cfg,
> >    	}
> > 
> >    	fib_info_cnt++;
> > +	refcount_set(&fi->fib_treeref, 1);
> >    	fi->fib_net = net;
> >    	fi->fib_protocol = cfg->fc_protocol;
> >    	fi->fib_scope = cfg->fc_scope;
> 
> Oops, it's already fixed in -next, so
> 
> #syz fix: ipv4: Fix refcount warning for new fib_info
> 
> 
> BTW: there is one more bug with refcounts:
> 
> link_it:
> 	ofi = fib_find_info(fi);
> 	if (ofi) {
> 		fi->fib_dead = 1;
> 		free_fib_info(fi);
> 		refcount_inc(&ofi->fib_treeref);
> 
> 		^^^^^^^^^^^^^^^^^^^^^^^
> 		/ *fib_treeref is 0 here */

Why 0? ofi is an existing object it's already initialized.

> 		return ofi;
> 	}
> 
> 	refcount_set(&fi->fib_treeref, 1);
> 
> 
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> index f29feb7772da..38d1fc4d0be1 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -1543,6 +1543,8 @@ struct fib_info *fib_create_info(struct fib_config 
> *cfg,
>   	}
> 
>   link_it:
> +	refcount_set(&fi->fib_treeref, 1);
> +
>   	ofi = fib_find_info(fi);
>   	if (ofi) {
>   		fi->fib_dead = 1;
> @@ -1551,7 +1553,6 @@ struct fib_info *fib_create_info(struct fib_config 
> *cfg,
>   		return ofi;
>   	}
> 
> -	refcount_set(&fi->fib_treeref, 1);
>   	refcount_set(&fi->fib_clntref, 1);
>   	spin_lock_bh(&fib_info_lock);
>   	hlist_add_head(&fi->fib_hash,
> 
> 
> Thoughts?


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] net-next boot error: WARNING: refcount bug in fib_create_info
  2021-08-03 21:04     ` Jakub Kicinski
@ 2021-08-03 22:32       ` David Ahern
  2021-08-04  5:05       ` Pavel Skripkin
  1 sibling, 0 replies; 6+ messages in thread
From: David Ahern @ 2021-08-03 22:32 UTC (permalink / raw)
  To: Jakub Kicinski, Pavel Skripkin
  Cc: syzbot, davem, dsahern, linux-kernel, netdev, syzkaller-bugs, yoshfuji

On 8/3/21 3:04 PM, Jakub Kicinski wrote:
>>>
>>> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
>>> index f29feb7772da..bb9949f6bb70 100644
>>> --- a/net/ipv4/fib_semantics.c
>>> +++ b/net/ipv4/fib_semantics.c
>>> @@ -1428,6 +1428,7 @@ struct fib_info *fib_create_info(struct fib_config
>>> *cfg,
>>>    	}
>>>
>>>    	fib_info_cnt++;
>>> +	refcount_set(&fi->fib_treeref, 1);
>>>    	fi->fib_net = net;
>>>    	fi->fib_protocol = cfg->fc_protocol;
>>>    	fi->fib_scope = cfg->fc_scope;
>>
>> Oops, it's already fixed in -next, so
>>
>> #syz fix: ipv4: Fix refcount warning for new fib_info
>>
>>
>> BTW: there is one more bug with refcounts:
>>
>> link_it:
>> 	ofi = fib_find_info(fi);
>> 	if (ofi) {
>> 		fi->fib_dead = 1;
>> 		free_fib_info(fi);
>> 		refcount_inc(&ofi->fib_treeref);
>>
>> 		^^^^^^^^^^^^^^^^^^^^^^^
>> 		/ *fib_treeref is 0 here */
> 
> Why 0? ofi is an existing object it's already initialized.

yes, it is an existing object with a non-0 refcount.

> 
>> 		return ofi;
>> 	}
>>
>> 	refcount_set(&fi->fib_treeref, 1);
>>
>>
>> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
>> index f29feb7772da..38d1fc4d0be1 100644
>> --- a/net/ipv4/fib_semantics.c
>> +++ b/net/ipv4/fib_semantics.c
>> @@ -1543,6 +1543,8 @@ struct fib_info *fib_create_info(struct fib_config 
>> *cfg,
>>   	}
>>
>>   link_it:
>> +	refcount_set(&fi->fib_treeref, 1);

moving the refcount_set here causes all kinds of problems with the
release and error paths in this function.


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [syzbot] net-next boot error: WARNING: refcount bug in fib_create_info
  2021-08-03 21:04     ` Jakub Kicinski
  2021-08-03 22:32       ` David Ahern
@ 2021-08-04  5:05       ` Pavel Skripkin
  1 sibling, 0 replies; 6+ messages in thread
From: Pavel Skripkin @ 2021-08-04  5:05 UTC (permalink / raw)
  To: Jakub Kicinski
  Cc: syzbot, davem, dsahern, linux-kernel, netdev, syzkaller-bugs, yoshfuji

On Tue, 3 Aug 2021 14:04:35 -0700
Jakub Kicinski <kuba@kernel.org> wrote:

> On Tue, 3 Aug 2021 19:31:50 +0300 Pavel Skripkin wrote:
> > On 8/3/21 7:12 PM, Pavel Skripkin wrote:
> > > On 8/3/21 7:07 PM, syzbot wrote:  
> > >> Hello,
> > >> 
> > >> syzbot found the following issue on:
> > >> 
> > >> HEAD commit:    1187c8c4642d net: phy: mscc: make some arrays
> > >> static const.. git tree:       net-next
> > >> console output:
> > >> https://syzkaller.appspot.com/x/log.txt?x=140e7b3e300000 kernel
> > >> config:
> > >> https://syzkaller.appspot.com/x/.config?x=f9bb42efdc6f1d7
> > >> dashboard link:
> > >> https://syzkaller.appspot.com/bug?extid=c5ac86461673ef58847c
> > >> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld
> > >> (GNU Binutils for Debian) 2.35.1
> > >> 
> > >> IMPORTANT: if you fix the issue, please add the following tag to
> > >> the commit: Reported-by:
> > >> syzbot+c5ac86461673ef58847c@syzkaller.appspotmail.com
> > >> 
> > >> FS-Cache: Netfs 'afs' registered for caching
> > >> Btrfs loaded, crc32c=crc32c-intel, assert=on, zoned=yes
> > >> Key type big_key registered
> > >> Key type encrypted registered
> > >> AppArmor: AppArmor sha1 policy hashing enabled
> > >> ima: No TPM chip found, activating TPM-bypass!
> > >> Loading compiled-in module X.509 certificates
> > >> Loaded X.509 cert 'Build time autogenerated kernel key:
> > >> f850c787ad998c396ae089c083b940ff0a9abb77' ima: Allocated hash
> > >> algorithm: sha256 ima: No architecture policies found
> > >> evm: Initialising EVM extended attributes:
> > >> evm: security.selinux (disabled)
> > >> evm: security.SMACK64 (disabled)
> > >> evm: security.SMACK64EXEC (disabled)
> > >> evm: security.SMACK64TRANSMUTE (disabled)
> > >> evm: security.SMACK64MMAP (disabled)
> > >> evm: security.apparmor
> > >> evm: security.ima
> > >> evm: security.capability
> > >> evm: HMAC attrs: 0x1
> > >> PM:   Magic number: 1:990:690
> > >> printk: console [netcon0] enabled
> > >> netconsole: network logging started
> > >> gtp: GTP module loaded (pdp ctx size 104 bytes)
> > >> rdma_rxe: loaded
> > >> cfg80211: Loading compiled-in X.509 certificates for regulatory
> > >> database cfg80211: Loaded X.509 cert 'sforshee:
> > >> 00b28ddf47aef9cea7' ALSA device list:
> > >>    #0: Dummy 1
> > >>    #1: Loopback 1
> > >>    #2: Virtual MIDI Card 1
> > >> md: Waiting for all devices to be available before autodetect
> > >> md: If you don't use raid, use raid=noautodetect
> > >> md: Autodetecting RAID arrays.
> > >> md: autorun ...
> > >> md: ... autorun DONE.
> > >> EXT4-fs (sda1): mounted filesystem without journal. Opts:
> > >> (null). Quota mode: none. VFS: Mounted root (ext4 filesystem)
> > >> readonly on device 8:1. devtmpfs: mounted
> > >> Freeing unused kernel image (initmem) memory: 4476K
> > >> Write protecting the kernel read-only data: 169984k
> > >> Freeing unused kernel image (text/rodata gap) memory: 2012K
> > >> Freeing unused kernel image (rodata/data gap) memory: 1516K
> > >> Run /sbin/init as init process
> > >> systemd[1]: systemd 232 running in system mode. (+PAM +AUDIT
> > >> +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP
> > >> +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD
> > >> +IDN) systemd[1]: Detected virtualization kvm. systemd[1]:
> > >> Detected architecture x86-64. systemd[1]: Set hostname to
> > >> <syzkaller>. ------------[ cut here ]------------ refcount_t:
> > >> addition on 0; use-after-free. WARNING: CPU: 1 PID: 1 at
> > >> lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0
> > >> lib/refcount.c:25 Modules linked in: CPU: 1 PID: 1 Comm: systemd
> > >> Not tainted 5.14.0-rc3-syzkaller #0 Hardware name: Google Google
> > >> Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > >> RIP: 0010:refcount_warn_saturate+0x169/0x1e0 lib/refcount.c:25
> > >> Code: 09 31 ff 89 de e8 d7 fa 9e fd 84 db 0f 85 36 ff ff ff e8
> > >> 8a f4 9e fd 48 c7 c7 c0 81 e3 89 c6 05 70 51 81 09 01 e8 48 f8
> > >> 13 05 <0f> 0b e9 17 ff ff ff e8 6b f4 9e fd 0f b6 1d 55 51 81 09
> > >> 31 ff 89 RSP: 0018:ffffc90000c66ab0 EFLAGS: 00010286 RAX:
> > >> 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> > >> RDX: ffff88813fe48000 RSI: ffffffff815d7b25 RDI:
> > >> fffff5200018cd48 RBP: 0000000000000002 R08: 0000000000000000
> > >> R09: 0000000000000001 R10: ffffffff815d195e R11:
> > >> 0000000000000000 R12: 0000000000000004 R13: 0000000000000001
> > >> R14: 0000000000000000 R15: ffff888027722e00 FS:
> > >> 00007f8c1c5d0500(0000) GS:ffff8880b9d00000(0000)
> > >> knlGS:0000000000000000 CS:  0010 DS: 0000 ES: 0000 CR0:
> > >> 0000000080050033 CR2: 000055ed0ced4368 CR3: 0000000026bac000
> > >> CR4: 00000000001506e0 DR0: 0000000000000000 DR1:
> > >> 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000
> > >> DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace:
> > >> __refcount_add include/linux/refcount.h:199 [inline]
> > >> __refcount_inc include/linux/refcount.h:250 [inline]
> > >> refcount_inc include/linux/refcount.h:267 [inline]
> > >> fib_create_info+0x36af/0x4910 net/ipv4/fib_semantics.c:1554  
> > > 
> > > Missed refcount_set(), I think
> > > 
> > > diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> > > index f29feb7772da..bb9949f6bb70 100644
> > > --- a/net/ipv4/fib_semantics.c
> > > +++ b/net/ipv4/fib_semantics.c
> > > @@ -1428,6 +1428,7 @@ struct fib_info *fib_create_info(struct
> > > fib_config *cfg,
> > >    	}
> > > 
> > >    	fib_info_cnt++;
> > > +	refcount_set(&fi->fib_treeref, 1);
> > >    	fi->fib_net = net;
> > >    	fi->fib_protocol = cfg->fc_protocol;
> > >    	fi->fib_scope = cfg->fc_scope;
> > 
> > Oops, it's already fixed in -next, so
> > 
> > #syz fix: ipv4: Fix refcount warning for new fib_info
> > 
> > 
> > BTW: there is one more bug with refcounts:
> > 
> > link_it:
> > 	ofi = fib_find_info(fi);
> > 	if (ofi) {
> > 		fi->fib_dead = 1;
> > 		free_fib_info(fi);
> > 		refcount_inc(&ofi->fib_treeref);
> > 
> > 		^^^^^^^^^^^^^^^^^^^^^^^
> > 		/ *fib_treeref is 0 here */
> 
> Why 0? ofi is an existing object it's already initialized.
> 

Yep, I see now, sorry for misinformation :(



With regards,
Pavel Skripkin

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2021-08-04  5:05 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-03 16:07 [syzbot] net-next boot error: WARNING: refcount bug in fib_create_info syzbot
2021-08-03 16:12 ` Pavel Skripkin
2021-08-03 16:31   ` Pavel Skripkin
2021-08-03 21:04     ` Jakub Kicinski
2021-08-03 22:32       ` David Ahern
2021-08-04  5:05       ` Pavel Skripkin

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