Re: WARNING in apparmor_secid_to_secctx

From: Stephen Smalley
Date: Fri Aug 31 2018 - 12:01:52 EST

On 08/29/2018 10:21 PM, Dmitry Vyukov wrote:
On Wed, Aug 29, 2018 at 7:17 PM, syzbot
<syzbot+21016130b0580a9de3b5@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

syzbot found the following crash on:

HEAD commit: 817e60a7a2bb Merge branch 'nfp-add-NFP5000-support'
git tree: net-next
console output:
kernel config:
dashboard link:
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+21016130b0580a9de3b5@xxxxxxxxxxxxxxxxxxxxxxxxx

Hi John, Tyler,

I've switched syzbot from selinux to apparmor as we discussed on lss:

Sorry, does this mean that you are no longer testing selinux via syzbot? That seems unfortunate. SELinux is default-enabled and used in Fedora, RHEL and all derivatives (e.g. CentOS), and mandatory in Android (and seemingly getting some use in ChromeOS now as well, at least for the Android container and possibly wider), so it seems unwise to drop it from your testing altogether. I was under the impression that you were just going to add apparmor to your testing matrix, not drop selinux altogether.

As expedited fix for this as possible would be nice to get, because we
are currently getting 1 machine crash/minute on this bug:

------------[ cut here ]------------
AppArmor WARN apparmor_secid_to_secctx: ((!secdata)):
WARNING: CPU: 0 PID: 14826 at security/apparmor/secid.c:82
apparmor_secid_to_secctx+0x2b5/0x2f0 security/apparmor/secid.c:82
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 14826 Comm: syz-executor1 Not tainted 4.19.0-rc1+ #193
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+0x1c9/0x2b4 lib/dump_stack.c:113
panic+0x238/0x4e7 kernel/panic.c:184
__warn.cold.8+0x163/0x1ba kernel/panic.c:536
report_bug+0x252/0x2d0 lib/bug.c:186
fixup_bug arch/x86/kernel/traps.c:178 [inline]
do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:993
RIP: 0010:apparmor_secid_to_secctx+0x2b5/0x2f0 security/apparmor/secid.c:82
Code: c7 c7 40 66 58 87 e8 6a 6d 0f fe 0f 0b e9 6c fe ff ff e8 3e aa 44 fe
48 c7 c6 80 67 58 87 48 c7 c7 a0 65 58 87 e8 4b 6d 0f fe <0f> 0b e9 3f fe ff
ff 48 89 df e8 fc a7 83 fe e9 ed fe ff ff bb f4
RSP: 0018:ffff8801ba1bed10 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff8801ba1beed0 RCX: ffffc9000227e000
RDX: 0000000000018482 RSI: ffffffff8163ac01 RDI: 0000000000000001
RBP: ffff8801ba1bed30 R08: ffff8801b80ec080 R09: ffffed003b603eca
R10: ffffed003b603eca R11: ffff8801db01f657 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8801ba1beed0
security_secid_to_secctx+0x63/0xc0 security/security.c:1314
ctnetlink_secctx_size net/netfilter/nf_conntrack_netlink.c:621 [inline]
ctnetlink_nlmsg_size net/netfilter/nf_conntrack_netlink.c:659 [inline]
nf_conntrack_event_report include/net/netfilter/nf_conntrack_ecache.h:112
nf_ct_delete+0x33c/0x5d0 net/netfilter/nf_conntrack_core.c:601
nf_ct_iterate_cleanup+0x48c/0x5e0 net/netfilter/nf_conntrack_core.c:1892
ctnetlink_flush_conntrack net/netfilter/nf_conntrack_netlink.c:1226
nfnetlink_rcv_msg+0xd88/0x1070 net/netfilter/nfnetlink.c:228
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2454
nfnetlink_rcv+0x1c0/0x4d0 net/netfilter/nfnetlink.c:560
netlink_unicast_kernel net/netlink/af_netlink.c:1317 [inline]
netlink_unicast+0x5a0/0x760 net/netlink/af_netlink.c:1343
netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1908
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:631
___sys_sendmsg+0x7fd/0x930 net/socket.c:2114
__sys_sendmsg+0x11d/0x290 net/socket.c:2152
__do_sys_sendmsg net/socket.c:2161 [inline]
__se_sys_sendmsg net/socket.c:2159 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2159
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
RIP: 0033:0x457089
Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7bc6e03c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f7bc6e046d4 RCX: 0000000000457089
RDX: 0000000000000000 RSI: 0000000020d65000 RDI: 0000000000000003
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d4588 R14: 00000000004c8d5c R15: 0000000000000000
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..

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