In testing I have not been able to reproduce.
But from the oops it looks either like potentially like memory corruption, or
corruption of the cred. The oops reports
invalid opcode: 0000 [#1] SMP
however the piece of code triggering this is used all the time, so the
more likely scenario is that the cred does not have the correct security
labeling which would trigger an oops. The oops would not normally be an
invalid opcode, but its possible the handling within the oops is
triggering the invalid opcode.
The line of code triggering this oops is
BUG_ON(!ctx || !ctx->label);
which going with the bad cred hypothesis means the actual problem is
else where. Tracing down the conditions that cause the bad cred may be
difficult.
With this being reported as fine in 14.04.5 with all 4.4.x kernels, and
without further input to help trace down the conditions that cause this,
I am inclined to close this bug as fixed.
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https://bugs.launchpad.net/bugs/1626984
Title:
kernel BUG at /build/linux-lts-xenial-_hWfOZ/linux-lts-
xenial-4.4.0/security/apparmor/include/context.h:69!
Status in linux package in Ubuntu:
Confirmed
Bug description:
I am runing sosreport on ubuntu 14.04.4 LTS which has upgrade the kernel to
4.4.0-38-generic, it get oops while copying
/sys/module/apparmor/parameters/audit. and it also can be triggered with
cat /sys/module/apparmor/parameters/audit.
[ 213.174092] ------------[ cut here ]------------
[ 213.174130] kernel BUG at
/build/linux-lts-xenial-_hWfOZ/linux-lts-xenial-4.4.0/security/apparmor/include/context.h:69!
[ 213.174187] invalid opcode: 0000 [#1] SMP
[ 213.174215] Modules linked in: ppdev lp joydev serio_raw parport_pc
parport psmouse virtio_scsi floppy
[ 213.174283] CPU: 0 PID: 2246 Comm: cat Not tainted 4.4.0-38-generic
#57~14.04.1-Ubuntu
[ 213.174324] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014
[ 213.174380] task: ffff880037b15780 ti: ffff8800399c4000 task.ti:
ffff8800399c4000
[ 213.174419] RIP: 0010:[<ffffffff813888a1>] [<ffffffff813888a1>]
aa_current_raw_label.part.6+0x4/0x6
[ 213.174478] RSP: 0018:ffff8800399c7d60 EFLAGS: 00010246
[ 213.174506] RAX: 0000000000000000 RBX: ffff88003a426000 RCX:
ffff88003e3802a0
[ 213.174542] RDX: ffff88003a426000 RSI: ffffffff81ddc0d8 RDI:
ffff88003a426000
[ 213.174578] RBP: ffff8800399c7d60 R08: ffff88003e3802a0 R09:
0000000000000000
[ 213.174614] R10: 0000000000001000 R11: 0000000000000246 R12:
ffffffff81e44ae0
[ 213.174658] R13: ffff88003e3802a0 R14: ffffffff81e4c220 R15:
ffff88003c2b2e40
[ 213.174702] FS: 00007f7bea106740(0000) GS:ffff88003fc00000(0000)
knlGS:0000000000000000
[ 213.174743] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 213.174781] CR2: 0000000000a40038 CR3: 000000003cdfa000 CR4:
00000000000006f0
[ 213.174819] Stack:
[ 213.174832] ffff8800399c7d88 ffffffff8136d58a ffff88003a426000
ffff88003a426000
[ 213.174885] ffff88003e3802a0 ffff8800399c7da0 ffffffff8136fda2
ffff88003e39c5f0
[ 213.174928] ffff8800399c7dd0 ffffffff8109a7e4 ffff88003c2b2e40
ffffffff81a170c0
[ 213.174971] Call Trace:
[ 213.174996] [<ffffffff8136d58a>] policy_view_capable+0x1ba/0x220
[ 213.175030] [<ffffffff8136fda2>] param_get_audit+0x12/0x50
[ 213.175062] [<ffffffff8109a7e4>] param_attr_show+0x54/0xa0
[ 213.175092] [<ffffffff8109a20d>] module_attr_show+0x1d/0x30
[ 213.175130] [<ffffffff8127a6e2>] sysfs_kf_seq_show+0xc2/0x1a0
[ 213.175162] [<ffffffff81278f73>] kernfs_seq_show+0x23/0x30
[ 213.175199] [<ffffffff81220d55>] seq_read+0xe5/0x350
[ 213.175227] [<ffffffff8127970d>] kernfs_fop_read+0x10d/0x170
[ 213.176170] [<ffffffff811fda18>] __vfs_read+0x18/0x40
[ 213.177101] [<ffffffff811fdfcf>] vfs_read+0x7f/0x130
[ 213.178016] [<ffffffff811feda6>] SyS_read+0x46/0xa0
[ 213.178932] [<ffffffff817fa336>] entry_SYSCALL_64_fastpath+0x16/0x75
[ 213.179814] Code: 80 3d 1a 7f b8 00 00 75 1d 55 be 2e 00 00 00 48 c7 c7 f0
2f cb 81 48 89 e5 e8 7c 50 cf ff 5d c6 05 fb 7e b8 00 01 c3 55 48 89 e5 <0f> 0b
b8 01 00 00 00 3e 0f c1 07 ff c0 ff c8 7f 26 80 3d df 7e
[ 213.182634] RIP [<ffffffff813888a1>] aa_current_raw_label.part.6+0x4/0x6
[ 213.183528] RSP <ffff8800399c7d60>
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