Revision 624f5ab8720b3371367327a822c267699c1823b8 authored by Eric Biggers on 07 November 2017, 22:29:02 UTC, committed by James Morris on 08 November 2017, 13:38:21 UTC
syzkaller reported a NULL pointer dereference in asn1_ber_decoder(). It can be reproduced by the following command, assuming CONFIG_PKCS7_TEST_KEY=y: keyctl add pkcs7_test desc '' @s The bug is that if the data buffer is empty, an integer underflow occurs in the following check: if (unlikely(dp >= datalen - 1)) goto data_overrun_error; This results in the NULL data pointer being dereferenced. Fix it by checking for 'datalen - dp < 2' instead. Also fix the similar check for 'dp >= datalen - n' later in the same function. That one possibly could result in a buffer overread. The NULL pointer dereference was reproducible using the "pkcs7_test" key type but not the "asymmetric" key type because the "asymmetric" key type checks for a 0-length payload before calling into the ASN.1 decoder but the "pkcs7_test" key type does not. The bug report was: BUG: unable to handle kernel NULL pointer dereference at (null) IP: asn1_ber_decoder+0x17f/0xe60 lib/asn1_decoder.c:233 PGD 7b708067 P4D 7b708067 PUD 7b6ee067 PMD 0 Oops: 0000 [#1] SMP Modules linked in: CPU: 0 PID: 522 Comm: syz-executor1 Not tainted 4.14.0-rc8 #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.3-20171021_125229-anatol 04/01/2014 task: ffff9b6b3798c040 task.stack: ffff9b6b37970000 RIP: 0010:asn1_ber_decoder+0x17f/0xe60 lib/asn1_decoder.c:233 RSP: 0018:ffff9b6b37973c78 EFLAGS: 00010216 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000021c RDX: ffffffff814a04ed RSI: ffffb1524066e000 RDI: ffffffff910759e0 RBP: ffff9b6b37973d60 R08: 0000000000000001 R09: ffff9b6b3caa4180 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f10ed1f2700(0000) GS:ffff9b6b3ea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000007b6f3000 CR4: 00000000000006f0 Call Trace: pkcs7_parse_message+0xee/0x240 crypto/asymmetric_keys/pkcs7_parser.c:139 verify_pkcs7_signature+0x33/0x180 certs/system_keyring.c:216 pkcs7_preparse+0x41/0x70 crypto/asymmetric_keys/pkcs7_key_type.c:63 key_create_or_update+0x180/0x530 security/keys/key.c:855 SYSC_add_key security/keys/keyctl.c:122 [inline] SyS_add_key+0xbf/0x250 security/keys/keyctl.c:62 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x4585c9 RSP: 002b:00007f10ed1f1bd8 EFLAGS: 00000216 ORIG_RAX: 00000000000000f8 RAX: ffffffffffffffda RBX: 00007f10ed1f2700 RCX: 00000000004585c9 RDX: 0000000020000000 RSI: 0000000020008ffb RDI: 0000000020008000 RBP: 0000000000000000 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000216 R12: 00007fff1b2260ae R13: 00007fff1b2260af R14: 00007f10ed1f2700 R15: 0000000000000000 Code: dd ca ff 48 8b 45 88 48 83 e8 01 4c 39 f0 0f 86 a8 07 00 00 e8 53 dd ca ff 49 8d 46 01 48 89 85 58 ff ff ff 48 8b 85 60 ff ff ff <42> 0f b6 0c 30 89 c8 88 8d 75 ff ff ff 83 e0 1f 89 8d 28 ff ff RIP: asn1_ber_decoder+0x17f/0xe60 lib/asn1_decoder.c:233 RSP: ffff9b6b37973c78 CR2: 0000000000000000 Fixes: 42d5ec27f873 ("X.509: Add an ASN.1 decoder") Reported-by: syzbot <syzkaller@googlegroups.com> Cc: <stable@vger.kernel.org> # v3.7+ Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
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accounting | ||
acpi | ||
admin-guide | ||
aoe | ||
arm | ||
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auxdisplay | ||
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cdrom | ||
cgroup-v1 | ||
cma | ||
connector | ||
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core-api | ||
cpu-freq | ||
cpuidle | ||
cris | ||
crypto | ||
dev-tools | ||
device-mapper | ||
devicetree | ||
dmaengine | ||
doc-guide | ||
driver-api | ||
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extcon | ||
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gpu | ||
hid | ||
hwmon | ||
i2c | ||
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ide | ||
iio | ||
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input | ||
ioctl | ||
isdn | ||
kbuild | ||
kdump | ||
kernel-hacking | ||
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livepatch | ||
locking | ||
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target | ||
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Changes | l--------- | 19 bytes |
CodingStyle | -rw-r--r-- | 48 bytes |
DMA-API-HOWTO.txt | -rw-r--r-- | 34.1 KB |
DMA-API.txt | -rw-r--r-- | 27.6 KB |
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Makefile | -rw-r--r-- | 4.2 KB |
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SM501.txt | -rw-r--r-- | 2.8 KB |
SubmittingPatches | -rw-r--r-- | 54 bytes |
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debugging-modules.txt | -rw-r--r-- | 954 bytes |
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hwspinlock.txt | -rw-r--r-- | 12.5 KB |
index.rst | -rw-r--r-- | 2.7 KB |
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io-mapping.txt | -rw-r--r-- | 3.3 KB |
io_ordering.txt | -rw-r--r-- | 2.0 KB |
iostats.txt | -rw-r--r-- | 8.1 KB |
irqflags-tracing.txt | -rw-r--r-- | 2.3 KB |
isa.txt | -rw-r--r-- | 5.1 KB |
isapnp.txt | -rw-r--r-- | 492 bytes |
kernel-doc-nano-HOWTO.txt | -rw-r--r-- | 10.3 KB |
kernel-per-CPU-kthreads.txt | -rw-r--r-- | 13.3 KB |
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mailbox.txt | -rw-r--r-- | 4.4 KB |
memory-barriers.txt | -rw-r--r-- | 113.0 KB |
memory-hotplug.txt | -rw-r--r-- | 18.6 KB |
men-chameleon-bus.txt | -rw-r--r-- | 5.7 KB |
nommu-mmap.txt | -rw-r--r-- | 12.4 KB |
ntb.txt | -rw-r--r-- | 10.8 KB |
numastat.txt | -rw-r--r-- | 1.0 KB |
padata.txt | -rw-r--r-- | 7.4 KB |
parport-lowlevel.txt | -rw-r--r-- | 37.1 KB |
percpu-rw-semaphore.txt | -rw-r--r-- | 1.1 KB |
phy.txt | -rw-r--r-- | 7.8 KB |
pi-futex.txt | -rw-r--r-- | 5.7 KB |
pnp.txt | -rw-r--r-- | 7.0 KB |
preempt-locking.txt | -rw-r--r-- | 5.6 KB |
printk-formats.txt | -rw-r--r-- | 12.5 KB |
pwm.txt | -rw-r--r-- | 6.2 KB |
rbtree.txt | -rw-r--r-- | 14.8 KB |
remoteproc.txt | -rw-r--r-- | 12.6 KB |
rfkill.txt | -rw-r--r-- | 5.0 KB |
robust-futex-ABI.txt | -rw-r--r-- | 8.7 KB |
robust-futexes.txt | -rw-r--r-- | 9.5 KB |
rpmsg.txt | -rw-r--r-- | 13.1 KB |
rtc.txt | -rw-r--r-- | 10.6 KB |
sgi-ioc4.txt | -rw-r--r-- | 2.1 KB |
siphash.txt | -rw-r--r-- | 6.3 KB |
smsc_ece1099.txt | -rw-r--r-- | 2.5 KB |
static-keys.txt | -rw-r--r-- | 13.0 KB |
svga.txt | -rw-r--r-- | 14.1 KB |
switchtec.txt | -rw-r--r-- | 3.1 KB |
sync_file.txt | -rw-r--r-- | 3.1 KB |
tee.txt | -rw-r--r-- | 5.2 KB |
this_cpu_ops.txt | -rw-r--r-- | 11.2 KB |
unaligned-memory-access.txt | -rw-r--r-- | 10.4 KB |
vfio-mediated-device.txt | -rw-r--r-- | 14.3 KB |
vfio.txt | -rw-r--r-- | 21.3 KB |
video-output.txt | -rw-r--r-- | 1.1 KB |
xillybus.txt | -rw-r--r-- | 17.6 KB |
xz.txt | -rw-r--r-- | 5.5 KB |
zorro.txt | -rw-r--r-- | 2.9 KB |
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