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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 4.9 48/74] KEYS: DNS: limit the length of option strings
Date: Fri, 27 Apr 2018 15:58:38 +0200	[thread overview]
Message-ID: <20180427135711.922951437@linuxfoundation.org> (raw)
In-Reply-To: <20180427135709.899303463@linuxfoundation.org>

4.9-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: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-27 13:57 [PATCH 4.9 00/74] 4.9.97-stable review Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 01/74] cifs: do not allow creating sockets except with SMB1 posix exensions Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 02/74] x86/tsc: Prevent 32bit truncation in calc_hpet_ref() Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 03/74] drm/vc4: Fix memory leak during BO teardown Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 04/74] drm/i915: Fix LSPCON TMDS output buffer enabling from low-power state Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 05/74] i2c: i801: store and restore the SLVCMD register at load and unload Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 06/74] i2c: i801: Save register SMBSLVCMD value only once Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 07/74] i2c: i801: Restore configuration at shutdown Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 08/74] usb: musb: fix enumeration after resume Greg Kroah-Hartman
2018-04-27 13:57 ` [PATCH 4.9 09/74] usb: musb: call pm_runtime_{get,put}_sync before reading vbus registers Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 10/74] usb: musb: Fix external abort in musb_remove on omap2430 Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 11/74] MIPS: Generic: Fix big endian CPUs on generic machine Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 12/74] Input: drv260x - fix initializing overdrive voltage Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 13/74] power: supply: bq2415x: check for NULL acpi_id to avoid null pointer dereference Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 14/74] [media] stk-webcam: fix an endian bug in stk_camera_read_reg() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 15/74] OF: Prevent unaligned access in of_alias_scan() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 16/74] ath9k_hw: check if the chip failed to wake up Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 17/74] jbd2: fix use after free in kjournald2() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 18/74] Revert "perf tools: Decompress kernel module when reading DSO data" Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 19/74] perf: Fix sample_max_stack maximum check Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 20/74] perf: Return proper values for user stack errors Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 21/74] RDMA/mlx5: Fix NULL dereference while accessing XRC_TGT QPs Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 22/74] drm/i915/bxt, glk: Increase PCODE timeouts during CDCLK freq changing Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 23/74] mac80211_hwsim: fix use-after-free bug in hwsim_exit_net Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 24/74] r8152: add Linksys USB3GIGV1 id Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 25/74] Revert "pinctrl: intel: Initialize GPIO properly when used through irqchip" Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 26/74] Revert "ath10k: send (re)assoc peer command when NSS changed" Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 27/74] PCI: Wait up to 60 seconds for device to become ready after FLR Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 28/74] s390: introduce CPU alternatives Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 29/74] s390: enable CPU alternatives unconditionally Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 30/74] KVM: s390: wire up bpb feature Greg Kroah-Hartman
2018-04-27 15:43   ` Christian Borntraeger
2018-04-27 13:58 ` [PATCH 4.9 31/74] s390: scrub registers on kernel entry and KVM exit Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 32/74] s390: add optimized array_index_mask_nospec Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 33/74] s390/alternative: use a copy of the facility bit mask Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 34/74] s390: add options to change branch prediction behaviour for the kernel Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 35/74] s390: run user space and KVM guests with modified branch prediction Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 36/74] s390: introduce execute-trampolines for branches Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 37/74] KVM: s390: force bp isolation for VSIE Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 38/74] s390: Replace IS_ENABLED(EXPOLINE_*) with IS_ENABLED(CONFIG_EXPOLINE_*) Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 39/74] s390: do not bypass BPENTER for interrupt system calls Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 40/74] s390/entry.S: fix spurious zeroing of r0 Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 41/74] s390: move nobp parameter functions to nospec-branch.c Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 42/74] s390: add automatic detection of the spectre defense Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 43/74] s390: report spectre mitigation via syslog Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 44/74] s390: add sysfs attributes for spectre Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 45/74] s390: correct nospec auto detection init order Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 46/74] s390: correct module section names for expoline code revert Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 47/74] bonding: do not set slave_dev npinfo before slave_enable_netpoll in bond_enslave Greg Kroah-Hartman
2018-04-27 13:58 ` Greg Kroah-Hartman [this message]
2018-04-27 13:58 ` [PATCH 4.9 49/74] l2tp: check sockaddr length in pppol2tp_connect() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 50/74] net: validate attribute sizes in neigh_dump_table() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 51/74] llc: delete timers synchronously in llc_sk_free() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 52/74] tcp: dont read out-of-bounds opsize Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 53/74] team: avoid adding twice the same option to the event list Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 54/74] team: fix netconsole setup over team Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 55/74] packet: fix bitfield update race Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 56/74] tipc: add policy for TIPC_NLA_NET_ADDR Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 57/74] pppoe: check sockaddr length in pppoe_connect() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 58/74] vlan: Fix reading memory beyond skb->tail in skb_vlan_tagged_multi Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 59/74] sctp: do not check port in sctp_inet6_cmp_addr Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 60/74] net: sched: ife: signal not finding metaid Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 61/74] llc: hold llc_sap before release_sock() Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 62/74] llc: fix NULL pointer deref for SOCK_ZAPPED Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 63/74] net: ethernet: ti: cpsw: fix tx vlan priority mapping Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 64/74] net: fix deadlock while clearing neighbor proxy table Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 65/74] tcp: md5: reject TCP_MD5SIG or TCP_MD5SIG_EXT on established sockets Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 66/74] net: af_packet: fix race in PACKET_{R|T}X_RING Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 67/74] ipv6: add RTA_TABLE and RTA_PREFSRC to rtm_ipv6_policy Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 68/74] strparser: Fix incorrect strp->need_bytes value Greg Kroah-Hartman
2018-04-27 13:58 ` [PATCH 4.9 69/74] scsi: mptsas: Disable WRITE SAME Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 70/74] cdrom: information leak in cdrom_ioctl_media_changed() Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 71/74] s390/cio: update chpid descriptor after resource accessibility event Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 72/74] s390/dasd: fix IO error for newly defined devices Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 73/74] s390/uprobes: implement arch_uretprobe_is_alive() Greg Kroah-Hartman
2018-04-27 13:59 ` [PATCH 4.9 74/74] ACPI / video: Only default only_lcd to true on Win8-ready _desktops_ Greg Kroah-Hartman
2018-04-27 18:13 ` [PATCH 4.9 00/74] 4.9.97-stable review Shuah Khan
2018-04-27 20:33 ` Dan Rue
2018-04-27 20:44 ` kernelci.org bot
2018-04-28 14:26 ` Guenter Roeck

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