On Mon, Feb 24, 2020 at 5:43 PM Eric Paris [off-list ref] wrote:

https://syzkaller.appspot.com/x/repro.syz?x=151b1109e00000 (the
reproducer listed) looks like it is literally fuzzing the AUDIT_SET.
Which seems like this is working as designed if it is setting the
failure mode to 2.

So it is, good catch :)  I saw the panic and instinctively chalked
that up to a mistaken config, not expecting that it was what was being
tested.

On Mon, 2020-02-24 at 17:38 -0500, Paul Moore wrote:

quoted

On Mon, Feb 24, 2020 at 3:18 AM syzbot
[off-list ref] wrote:

quoted

Hello,

syzbot found the following crash on:

HEAD commit:    36a44bcd Merge branch 'bnxt_en-shutdown-and-kexec-
kdump-re..
git tree:       net
console output:
https://syzkaller.appspot.com/x/log.txt?x=148bfdd9e00000
kernel config:
https://syzkaller.appspot.com/x/.config?x=768cc3d3e277cc16
dashboard link:
https://syzkaller.appspot.com/bug?extid=9a5e789e4725b9ef1316
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:
https://syzkaller.appspot.com/x/repro.syz?x=151b1109e00000
C reproducer:
https://syzkaller.appspot.com/x/repro.c?x=128bfdd9e00000

The bug was bisected to:

commit 0c1b9970ddd4cc41002321c3877e7f91aacb896d
Author: Dan Carpenter [off-list ref]
Date:   Fri Jul 28 14:42:27 2017 +0000

    staging: lustre: lustre: Off by two in lmv_fid2path()

bisection log:
https://syzkaller.appspot.com/x/bisect.txt?x=17e6c3e9e00000
final crash:
https://syzkaller.appspot.com/x/report.txt?x=1416c3e9e00000
console output:
https://syzkaller.appspot.com/x/log.txt?x=1016c3e9e00000

IMPORTANT: if you fix the bug, please add the following tag to the
commit:
Reported-by: syzbot+9a5e789e4725b9ef1316@syzkaller.appspotmail.com
Fixes: 0c1b9970ddd4 ("staging: lustre: lustre: Off by two in
lmv_fid2path()")

audit: audit_backlog=13 > audit_backlog_limit=7
audit: audit_lost=1 audit_rate_limit=0 audit_backlog_limit=7
Kernel panic - not syncing: audit: backlog limit exceeded
CPU: 1 PID: 9913 Comm: syz-executor024 Not tainted 5.6.0-rc1-
syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 audit_panic.cold+0x32/0x32 kernel/audit.c:307
 audit_log_lost kernel/audit.c:377 [inline]
 audit_log_lost+0x8b/0x180 kernel/audit.c:349
 audit_log_start kernel/audit.c:1788 [inline]
 audit_log_start+0x70e/0x7c0 kernel/audit.c:1745
 audit_log+0x95/0x120 kernel/audit.c:2345
 xt_replace_table+0x61d/0x830 net/netfilter/x_tables.c:1413
 __do_replace+0x1da/0x950 net/ipv6/netfilter/ip6_tables.c:1084
 do_replace net/ipv6/netfilter/ip6_tables.c:1157 [inline]
 do_ip6t_set_ctl+0x33a/0x4c8 net/ipv6/netfilter/ip6_tables.c:1681
 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
 nf_setsockopt+0x77/0xd0 net/netfilter/nf_sockopt.c:115
 ipv6_setsockopt net/ipv6/ipv6_sockglue.c:949 [inline]
 ipv6_setsockopt+0x147/0x180 net/ipv6/ipv6_sockglue.c:933
 tcp_setsockopt net/ipv4/tcp.c:3165 [inline]
 tcp_setsockopt+0x8f/0xe0 net/ipv4/tcp.c:3159
 sock_common_setsockopt+0x94/0xd0 net/core/sock.c:3149
 __sys_setsockopt+0x261/0x4c0 net/socket.c:2130
 __do_sys_setsockopt net/socket.c:2146 [inline]
 __se_sys_setsockopt net/socket.c:2143 [inline]
 __x64_sys_setsockopt+0xbe/0x150 net/socket.c:2143
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44720a
Code: 49 89 ca b8 37 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 1a e0
fb ff c3 66 0f 1f 84 00 00 00 00 00 49 89 ca b8 36 00 00 00 0f 05
<48> 3d 01 f0 ff ff 0f 83 fa df fb ff c3 66 0f 1f 84 00 00 00 00 00
RSP: 002b:00007ffd032dec78 EFLAGS: 00000286 ORIG_RAX:
0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000044720a
RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000003
RBP: 00007ffd032deda0 R08: 00000000000003b8 R09: 0000000000004000
R10: 00000000006d7b40 R11: 0000000000000286 R12: 00007ffd032deca0
R13: 00000000006d9d60 R14: 0000000000000029 R15: 00000000006d7ba0
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
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For information about bisection process see:
https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

Similar to syzbot report 72461ac44b36c98f58e5, see my comments there.

-- 
paul moore
www.paul-moore.com