Kernel 4.9.51 null pointer dereference add_rule with null key

Fri Aug 17 21:24:05 UTC 2018

Hey Paul,

My expectations are aligned to what you've pointed out already (not-vanilla
old kernel, user space client other than auditd).

Primarily what I'm looking for is a sanity check on the null pointer deref
on current vanilla kernel code because I think the rest of the issues stem
from that. My C isn't sharp enough to try my hand at a reproduction case,
though I would hope someone with the requisite expertise could put one
together relatively quickly. specifically this message:

audit: type=1305 audit(1534170894.852:117649234): auid=501 ses=102936
> op="add_rule" key=(null) list=4 res=0

On Fri, Aug 17, 2018 at 2:12 PM Paul Moore <paul at paul-moore.com> wrote:

> On Fri, Aug 17, 2018 at 4:26 PM Preston Bennes
> <preston.bennes at snowflake.net> wrote:
> > Hey Audit team,
>
> Hey Audit user!
>
> > 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)'.
>
> The first thing I need to comment on is that since this is a distro
> specific kernel (4.9.51-10.52.amzn1.x86_64) and not an upstream kernel
> there is a limit in the amount of help we can provide.  Generally the
> upstream list focuses on the upstream code and we leave support for
> the distro specific builds/packages up to the distro.  If you can
> reproduce your problem on an upstream kernel, with a strong preference
> for a *recent* upstream kernel, we can probably be of more help.  I
> simply don't know what patches Amazon merges into it's amzn1 kernels.
>
> With that out of the way, I will add that v4.9.x is a rather old
> kernel, and we've made a number of relevant improvements since the
> v4.9 release and it is unlikely all of them have been backported to
> your kernel.  If possible, I would suggest upgrading to a newer kernel
> as it may resolve your problem.
>
> There is also a possible issue of osquery as an auditd replacement;
> it's unlikely this is being caused by osquery, but we don't test with
> osquery to that save level as we do with Steve's audit userspace
> (auditd).
>
> > 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
> >
> > --
> > Linux-audit mailing list
> > Linux-audit at redhat.com
> > https://www.redhat.com/mailman/listinfo/linux-audit
>
> --
> paul moore
> www.paul-moore.com
>
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