tree 316d9c91e476291992c4aa37ae5462f867063da3
parent a3ed24cd28f2db6f6f5b2009565a2463c0df4af0
author John Johansen <john.johansen@canonical.com> 1511364818 -0800
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1512469591 +0100

apparmor: fix oops in audit_signal_cb hook

commit b12cbb21586277f72533769832c24cc6c1d60ab3 upstream.

The apparmor_audit_data struct ordering got messed up during a merge
conflict, resulting in the signal integer and peer pointer being in
a union instead of a struct.

For most of the 4.13 and 4.14 life cycle, this was hidden by
commit 651e28c5537a ("apparmor: add base infastructure for socket
mediation") which fixed the apparmor_audit_data struct when its data
was added. When that commit was reverted in -rc7 the signal audit bug
was exposed, and unfortunately it never showed up in any of the
testing until after 4.14 was released. Shaun Khan, Zephaniah
E. Loss-Cutler-Hull filed nearly simultaneous bug reports (with
different oopes, the smaller of which is included below).

Full credit goes to Tetsuo Handa for jumping on this as well and
noticing the audit data struct problem and reporting it.

[   76.178568] BUG: unable to handle kernel paging request at
ffffffff0eee3bc0
[   76.178579] IP: audit_signal_cb+0x6c/0xe0
[   76.178581] PGD 1a640a067 P4D 1a640a067 PUD 0
[   76.178586] Oops: 0000 [#1] PREEMPT SMP
[   76.178589] Modules linked in: fuse rfcomm bnep usblp uvcvideo btusb
btrtl btbcm btintel bluetooth ecdh_generic ip6table_filter ip6_tables
xt_tcpudp nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack
iptable_filter ip_tables x_tables intel_rapl joydev wmi_bmof serio_raw
iwldvm iwlwifi shpchp kvm_intel kvm irqbypass autofs4 algif_skcipher
nls_iso8859_1 nls_cp437 crc32_pclmul ghash_clmulni_intel
[   76.178620] CPU: 0 PID: 10675 Comm: pidgin Not tainted
4.14.0-f1-dirty #135
[   76.178623] Hardware name: Hewlett-Packard HP EliteBook Folio
9470m/18DF, BIOS 68IBD Ver. F.62 10/22/2015
[   76.178625] task: ffff9c7a94c31dc0 task.stack: ffffa09b02a4c000
[   76.178628] RIP: 0010:audit_signal_cb+0x6c/0xe0
[   76.178631] RSP: 0018:ffffa09b02a4fc08 EFLAGS: 00010292
[   76.178634] RAX: ffffa09b02a4fd60 RBX: ffff9c7aee0741f8 RCX:
0000000000000000
[   76.178636] RDX: ffffffffee012290 RSI: 0000000000000006 RDI:
ffff9c7a9493d800
[   76.178638] RBP: ffffa09b02a4fd40 R08: 000000000000004d R09:
ffffa09b02a4fc46
[   76.178641] R10: ffffa09b02a4fcb8 R11: ffff9c7ab44f5072 R12:
ffffa09b02a4fd40
[   76.178643] R13: ffffffff9e447be0 R14: ffff9c7a94c31dc0 R15:
0000000000000001
[   76.178646] FS:  00007f8b11ba2a80(0000) GS:ffff9c7afea00000(0000)
knlGS:0000000000000000
[   76.178648] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   76.178650] CR2: ffffffff0eee3bc0 CR3: 00000003d5209002 CR4:
00000000001606f0
[   76.178652] Call Trace:
[   76.178660]  common_lsm_audit+0x1da/0x780
[   76.178665]  ? d_absolute_path+0x60/0x90
[   76.178669]  ? aa_check_perms+0xcd/0xe0
[   76.178672]  aa_check_perms+0xcd/0xe0
[   76.178675]  profile_signal_perm.part.0+0x90/0xa0
[   76.178679]  aa_may_signal+0x16e/0x1b0
[   76.178686]  apparmor_task_kill+0x51/0x120
[   76.178690]  security_task_kill+0x44/0x60
[   76.178695]  group_send_sig_info+0x25/0x60
[   76.178699]  kill_pid_info+0x36/0x60
[   76.178703]  SYSC_kill+0xdb/0x180
[   76.178707]  ? preempt_count_sub+0x92/0xd0
[   76.178712]  ? _raw_write_unlock_irq+0x13/0x30
[   76.178716]  ? task_work_run+0x6a/0x90
[   76.178720]  ? exit_to_usermode_loop+0x80/0xa0
[   76.178723]  entry_SYSCALL_64_fastpath+0x13/0x94
[   76.178727] RIP: 0033:0x7f8b0e58b767
[   76.178729] RSP: 002b:00007fff19efd4d8 EFLAGS: 00000206 ORIG_RAX:
000000000000003e
[   76.178732] RAX: ffffffffffffffda RBX: 0000557f3e3c2050 RCX:
00007f8b0e58b767
[   76.178735] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
000000000000263b
[   76.178737] RBP: 0000000000000000 R08: 0000557f3e3c2270 R09:
0000000000000001
[   76.178739] R10: 000000000000022d R11: 0000000000000206 R12:
0000000000000000
[   76.178741] R13: 0000000000000001 R14: 0000557f3e3c13c0 R15:
0000000000000000
[   76.178745] Code: 48 8b 55 18 48 89 df 41 b8 20 00 08 01 5b 5d 48 8b
42 10 48 8b 52 30 48 63 48 4c 48 8b 44 c8 48 31 c9 48 8b 70 38 e9 f4 fd
00 00 <48> 8b 14 d5 40 27 e5 9e 48 c7 c6 7d 07 19 9f 48 89 df e8 fd 35
[   76.178794] RIP: audit_signal_cb+0x6c/0xe0 RSP: ffffa09b02a4fc08
[   76.178796] CR2: ffffffff0eee3bc0
[   76.178799] ---[ end trace 514af9529297f1a3 ]---

Fixes: cd1dbf76b23d ("apparmor: add the ability to mediate signals")
Reported-by: Zephaniah E. Loss-Cutler-Hull <warp-spam_kernel@aehallh.com>
Reported-by: Shuah Khan <shuahkh@osg.samsung.com>
Suggested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Tested-by: Ivan Kozik <ivan@ludios.org>
Tested-by: Zephaniah E. Loss-Cutler-Hull <warp-spam_kernel@aehallh.com>
Tested-by: Christian Boltz <apparmor@cboltz.de>
Tested-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>