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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>,
	Eric Biggers <ebiggers@google.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.14 11/80] KEYS: DNS: limit the length of option strings
Date: Fri, 27 Apr 2018 15:58:04 +0200	[thread overview]
Message-ID: <20180427135733.515538966@linuxfoundation.org> (raw)
In-Reply-To: <20180427135732.928644313@linuxfoundation.org>

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Biggers <ebiggers@google.com>


[ Upstream commit 9c438d7a3a52dcc2b9ed095cb87d3a5e83cf7e60 ]

Adding a dns_resolver key whose payload contains a very long option name
resulted in that string being printed in full.  This hit the WARN_ONCE()
in set_precision() during the printk(), because printk() only supports a
precision of up to 32767 bytes:

    precision 1000000 too large
    WARNING: CPU: 0 PID: 752 at lib/vsprintf.c:2189 vsnprintf+0x4bc/0x5b0

Fix it by limiting option strings (combined name + value) to a much more
reasonable 128 bytes.  The exact limit is arbitrary, but currently the
only recognized option is formatted as "dnserror=%lu" which fits well
within this limit.

Also ratelimit the printks.

Reproducer:

    perl -e 'print "#", "A" x 1000000, "\x00"' | keyctl padd dns_resolver desc @s

This bug was found using syzkaller.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Fixes: 4a2d789267e0 ("DNS: If the DNS server returns an error, allow that to be cached [ver #2]")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/dns_resolver/dns_key.c |   13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

--- a/net/dns_resolver/dns_key.c
+++ b/net/dns_resolver/dns_key.c
@@ -25,6 +25,7 @@
 #include <linux/moduleparam.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/ratelimit.h>
 #include <linux/kernel.h>
 #include <linux/keyctl.h>
 #include <linux/err.h>
@@ -91,9 +92,9 @@ dns_resolver_preparse(struct key_prepars
 
 			next_opt = memchr(opt, '#', end - opt) ?: end;
 			opt_len = next_opt - opt;
-			if (!opt_len) {
-				printk(KERN_WARNING
-				       "Empty option to dns_resolver key\n");
+			if (opt_len <= 0 || opt_len > 128) {
+				pr_warn_ratelimited("Invalid option length (%d) for dns_resolver key\n",
+						    opt_len);
 				return -EINVAL;
 			}
 
@@ -127,10 +128,8 @@ dns_resolver_preparse(struct key_prepars
 			}
 
 		bad_option_value:
-			printk(KERN_WARNING
-			       "Option '%*.*s' to dns_resolver key:"
-			       " bad/missing value\n",
-			       opt_nlen, opt_nlen, opt);
+			pr_warn_ratelimited("Option '%*.*s' to dns_resolver key: bad/missing value\n",
+					    opt_nlen, opt_nlen, opt);
 			return -EINVAL;
 		} while (opt = next_opt + 1, opt < end);
 	}

  parent reply	other threads:[~2018-04-27 13:58 UTC|newest]

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-27 13:57 [PATCH 4.14 00/80] 4.14.38-stable review Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.14 01/80] Revert "pinctrl: intel: Initialize GPIO properly when used through irqchip" Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.14 02/80] drm: bridge: dw-hdmi: Fix overflow workaround for Amlogic Meson GX SoCs Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.14 03/80] i40e: Fix attach VF to VM issue Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.14 04/80] tpm: cmd_ready command can be issued only after granting locality Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.14 05/80] tpm: tpm-interface: fix tpm_transmit/_cmd kdoc Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.14 06/80] tpm: add retry logic Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 07/80] Revert "ath10k: send (re)assoc peer command when NSS changed" Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 08/80] bonding: do not set slave_dev npinfo before slave_enable_netpoll in bond_enslave Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 09/80] ipv6: add RTA_TABLE and RTA_PREFSRC to rtm_ipv6_policy Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 10/80] ipv6: sr: fix NULL pointer dereference in seg6_do_srh_encap()- v4 pkts Greg Kroah-Hartman
2018-04-27 13:58 ` Greg Kroah-Hartman [this message]
2018-04-27 13:58 ` [PATCH 4.14 12/80] l2tp: check sockaddr length in pppol2tp_connect() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 13/80] net: validate attribute sizes in neigh_dump_table() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 14/80] llc: delete timers synchronously in llc_sk_free() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 15/80] tcp: dont read out-of-bounds opsize Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 16/80] net: af_packet: fix race in PACKET_{R|T}X_RING Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 17/80] tcp: md5: reject TCP_MD5SIG or TCP_MD5SIG_EXT on established sockets Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 18/80] net: fix deadlock while clearing neighbor proxy table Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 19/80] team: avoid adding twice the same option to the event list Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 20/80] net/smc: fix shutdown in state SMC_LISTEN Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 21/80] team: fix netconsole setup over team Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 22/80] packet: fix bitfield update race Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 23/80] tipc: add policy for TIPC_NLA_NET_ADDR Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 24/80] pppoe: check sockaddr length in pppoe_connect() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 25/80] vlan: Fix reading memory beyond skb->tail in skb_vlan_tagged_multi Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 26/80] amd-xgbe: Add pre/post auto-negotiation phy hooks Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 27/80] sctp: do not check port in sctp_inet6_cmp_addr Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 28/80] amd-xgbe: Improve KR auto-negotiation and training Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 29/80] strparser: Do not call mod_delayed_work with a timeout of LONG_MAX Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 30/80] amd-xgbe: Only use the SFP supported transceiver signals Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 31/80] strparser: Fix incorrect strp->need_bytes value Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 32/80] net: sched: ife: signal not finding metaid Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 33/80] tcp: clear tp->packets_out when purging write queue Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 34/80] net: sched: ife: handle malformed tlv length Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 35/80] net: sched: ife: check on metadata length Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 36/80] llc: hold llc_sap before release_sock() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 37/80] llc: fix NULL pointer deref for SOCK_ZAPPED Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 38/80] net: ethernet: ti: cpsw: fix tx vlan priority mapping Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 39/80] virtio_net: split out ctrl buffer Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 40/80] virtio_net: fix adding vids on big-endian Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 41/80] Revert "microblaze: fix endian handling" Greg Kroah-Hartman
2018-04-27 15:43   ` Guenter Roeck
2018-04-27 16:25   ` Guenter Roeck
2018-04-28  5:50     ` Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 42/80] s390: introduce CPU alternatives Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 43/80] s390: enable CPU alternatives unconditionally Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 44/80] KVM: s390: wire up bpb feature Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 45/80] s390: scrub registers on kernel entry and KVM exit Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 46/80] s390: add optimized array_index_mask_nospec Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 47/80] s390/alternative: use a copy of the facility bit mask Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 48/80] s390: add options to change branch prediction behaviour for the kernel Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 49/80] s390: run user space and KVM guests with modified branch prediction Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 50/80] s390: introduce execute-trampolines for branches Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 51/80] KVM: s390: force bp isolation for VSIE Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 52/80] s390: Replace IS_ENABLED(EXPOLINE_*) with IS_ENABLED(CONFIG_EXPOLINE_*) Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 53/80] s390: do not bypass BPENTER for interrupt system calls Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 54/80] s390/entry.S: fix spurious zeroing of r0 Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 55/80] s390: move nobp parameter functions to nospec-branch.c Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 56/80] s390: add automatic detection of the spectre defense Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 57/80] s390: report spectre mitigation via syslog Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 58/80] s390: add sysfs attributes for spectre Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 59/80] s390: correct nospec auto detection init order Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 60/80] s390: correct module section names for expoline code revert Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 61/80] microblaze: Setup dependencies for ASM optimized lib functions Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 62/80] arm64: dts: rockchip: remove vdd_log from rk3399-puma Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 63/80] Revert "mm/hmm: fix header file if/else/endif maze" Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 64/80] commoncap: Handle memory allocation failure Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 65/80] scsi: mptsas: Disable WRITE SAME Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.14 66/80] cdrom: information leak in cdrom_ioctl_media_changed() Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 67/80] fsnotify: Fix fsnotify_mark_connector race Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 68/80] m68k/mac: Dont remap SWIM MMIO region Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 69/80] block/swim: Check drive type Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 70/80] block/swim: Dont log an error message for an invalid ioctl Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 71/80] block/swim: Remove extra put_disk() call from error path Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 72/80] block/swim: Rename macros to avoid inconsistent inverted logic Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 73/80] block/swim: Select appropriate drive on device open Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 74/80] block/swim: Fix array bounds check Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 75/80] block/swim: Fix IO error at end of medium Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 76/80] tracing: Fix missing tab for hwlat_detector print format Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 77/80] s390/cio: update chpid descriptor after resource accessibility event Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 78/80] s390/dasd: fix IO error for newly defined devices Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 79/80] s390/uprobes: implement arch_uretprobe_is_alive() Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.14 80/80] ACPI / video: Only default only_lcd to true on Win8-ready _desktops_ Greg Kroah-Hartman
2018-04-27 18:14 ` [PATCH 4.14 00/80] 4.14.38-stable review Shuah Khan
2018-04-27 19:24 ` kernelci.org bot
2018-04-27 19:33 ` Nathan Chancellor
2018-04-28  5:06   ` Greg Kroah-Hartman
2018-04-27 20:37 ` Dan Rue
2018-04-28 14:28 ` Guenter Roeck

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