Kernel 4.9.51 null pointer dereference add_rule with null key

Fri Aug 17 20:04:11 UTC 2018

Hey Audit team,

I've got a kernel null pointer deref oops on Amazon Linux
kernel 4.9.51-10.52.amzn1.x86_64. After the oops all new cron processes
that spawned were stuck in D wait on some audit related syscall. This
exhausted system file handles and the box ended up needing to be rebooted
out-of-bounds. The audit handle was held by
https://github.com/facebook/osquery/.

It looks like there was an issue with audit sending to osquery
(netlink_unicast sending to pid 21233, error -111) followed by something
(presumably also osquery) attempting to 'op="add_rule" key=(null)'.

Here's from /var/log/messages.

Aug 13 14:34:54 packer_default-10-180-21-24 kernel: [4749520.133904] audit:
> netlink_unicast sending to audit_pid=21233 returned error: -111
> Aug 13 14:34:54 packer_default-10-180-21-24 kernel: [4749520.137982]
> audit_log_lost: 12 callbacks suppressed
> Aug 13 14:34:54 packer_default-10-180-21-24 kernel: [4749520.137983]
> audit: audit_lost=36081041 audit_rate_limit=8192 audit_backlog_limit=4096
> Aug 13 14:34:54 packer_default-10-180-21-24 kernel: [4749520.137985]
> audit: type=1305 audit(1534170894.852:117649229): audit_pid=21233 old=21233
> auid=501 ses=102936 res=0
> Aug 13 14:34:54 packer_default-10-180-21-24 kernel: [4749520.137986]
> audit: type=1305 audit(1534170894.852:117649230): audit_enabled=1 old=1
> auid=501 ses=102936 res=1
> Aug 13 14:34:54 packer_default-10-180-21-24 kernel: [4749520.137987]
> audit: type=1305 audit(1534170894.852:117649231): audit_backlog_wait_time=1
> old=1 auid=501 ses=102936 res=1
> Aug 13 14:34:54 packer_default-10-180-21-24 kernel: [4749520.137989]
> audit: type=1305 audit(1534170894.852:117649232): audit_backlog_limit=4096
> old=4096 auid=501 ses=102936 res=1
> Aug 13 14:34:54 packer_default-10-180-21-24 kernel: [4749520.137990]
> audit: type=1305 audit(1534170894.852:117649233): audit_failure=0 old=0
> auid=501 ses=102936 res=1
> Aug 13 14:34:54 packer_default-10-180-21-24 kernel: [4749520.137991]
> audit: type=1305 audit(1534170894.852:117649234): auid=501 ses=102936
> op="add_rule" key=(null) list=4 res=0
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.138007] BUG:
> unable to handle kernel NULL pointer dereference at 00000000000001e0
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.143872] IP:
> [<ffffffff814a76da>] netlink_unicast+0x4a/0x230
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.148336] PGD 0
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.149822]
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.151230] Oops:
> 0000 [#1] SMP
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.153736]
> Modules linked in: iptable_filter(E) ip_tables(E) x_tables(E) udp_diag(E)
> nfnetlink_queue(E) nfnetlink_log(E) nfnetlink(E) tcp_diag(E) inet_diag(E)
> isofs(E) ipv6(E) crc_
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.184036] CPU:
> 0 PID: 21372 Comm: osqueryd Tainted: G            E
>  4.9.51-10.52.amzn1.x86_64 #1
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.190620]
> Hardware name: Xen HVM domU, BIOS 4.2.amazon 08/24/2006
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.195513] task:
> ffff8807fa1c3b00 task.stack: ffffc900079a4000
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.200179] RIP:
> 0010:[<ffffffff814a76da>]  [<ffffffff814a76da>] netlink_unicast+0x4a/0x230
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.206822] RSP:
> 0018:ffffc900079a7c38  EFLAGS: 00010246
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.211065] RAX:
> 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.216779] RDX:
> 00001ffffffffffe RSI: 00000000024000c0 RDI: 0000000000000014
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.222473] RBP:
> ffffc900079a7c68 R08: 0000000000000004 R09: ffff88062a375414
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.228167] R10:
> ffff8808004032c0 R11: ffff88062a375400 R12: 0000000000000000
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.233738] R13:
> ffff8804200a0100 R14: 00000000000052f1 R15: 0000000000016d42
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.238999] FS:
> 00007f3d40cc4700(0000) GS:ffff880800a00000(0000) knlGS:0000000000000000
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.244796] CS:
> 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.249555] CR2:
> 00000000000001e0 CR3: 000000059e63d000 CR4: 00000000001406f0
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.255401] DR0:
> 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.260725] DR3:
> 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.266038] Stack:
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.267680]
> 00000000079a7c58 00000000000052f1 00000000000052f1 00000000ffffffa1
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.273540]
> ffff88062a376800 ffff8804200a1d00 ffffc900079a7cf8 ffffffff811107d2
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.279379]
> ffffc90000000004 ffffffff811e2f85 ffffc900079a7ca8 ffffffff8145a08c
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.285201] Call
> Trace:
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.287137]
> [<ffffffff811107d2>] audit_receive_msg+0x992/0xc20
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.291561]
> [<ffffffff811e2f85>] ? __kmalloc_node_track_caller+0x35/0x260
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.296642]
> [<ffffffff8145a08c>] ? release_sock+0x8c/0xa0
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.300718]
> [<ffffffff81110ab2>] audit_receive+0x52/0xa0
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.304713]
> [<ffffffff814a77ef>] netlink_unicast+0x15f/0x230
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.308943]
> [<ffffffff814a7bdc>] netlink_sendmsg+0x31c/0x390
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.313236]
> [<ffffffff81455818>] sock_sendmsg+0x38/0x50
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.317219]
> [<ffffffff81455c4f>] SYSC_sendto+0xef/0x170
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.321142]
> [<ffffffff811156ab>] ? __audit_syscall_entry+0xeb/0x100
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.325853]
> [<ffffffff81003437>] ? syscall_trace_enter+0x1b7/0x290
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.330464]
> [<ffffffff811158b3>] ? __audit_syscall_exit+0x1f3/0x280
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.335189]
> [<ffffffff8145673e>] SyS_sendto+0xe/0x10
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.338952]
> [<ffffffff81003854>] do_syscall_64+0x54/0xc0
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.342995]
> [<ffffffff8153d32b>] entry_SYSCALL64_slow_path+0x25/0x25
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.347840] Code:
> 65 8b 05 a2 5b b6 7e 25 00 ff 00 00 83 f8 01 19 f6 81 e6 a0 00 38 00 81 c6
> 20 00 08 02 e8 af cf ff ff 49 89 c5 31 c0 85 db 75 08 <49> 8b 84 24 e0 01
> 00 00 48 89 45
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.368625] RIP
> [<ffffffff814a76da>] netlink_unicast+0x4a/0x230
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.373253]  RSP
> <ffffc900079a7c38>
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.376013] CR2:
> 00000000000001e0
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.379307] ---[
> end trace 6a41b2274729ba2a ]---
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.663029]
> audit: type=1300 audit(1534170895.379:117649235): arch=c000003e syscall=59
> success=yes exit=0 a0=271cce0 a1=2741dd0 a2=26dc3b0 a3=7ffdd7f1ea80 items=2
> ppid=4556 pid=2407
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.682741]
> audit: type=1309 audit(1534170895.379:117649235): argc=2 a0="date" a1="+%s"
> Aug 13 14:34:55 packer_default-10-180-21-24 kernel: [4749520.688585]
> audit: type=1307 audit(1534170895.379:117649235): cwd="/"
> Aug 13 14:34:55 packer_default-10-180-21-24 abrt-dump-oops: Reported 1
> kernel oopses to Abrt
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