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general protection fault in override_creds

Status: fixed on 2020/01/08 01:06
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com
Fix commit: 0b8c0ec7eedc io_uring: use current task creds instead of allocating a new one
First crash: 1600d, last: 1596d
Cause bisection: introduced by (bisect log) :
commit 181e448d8709e517c9c7b523fcd209f24eb38ca7
Author: Jens Axboe <axboe@kernel.dk>
Date: Mon Nov 25 15:52:30 2019 +0000

  io_uring: async workers should inherit the user creds

Crash: general protection fault in override_creds (log)
Repro: C syz .config
  
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
[PATCH 5.4 000/191] 5.4.9-stable review 204 (204) 2020/01/08 18:26
[PATCH] io_uring: use current task creds instead of allocating a new one 1 (1) 2019/12/03 02:50
general protection fault in override_creds 3 (5) 2019/12/02 15:49

Sample crash report:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9217 Comm: io_uring-sq Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:creds_are_invalid kernel/cred.c:792 [inline]
RIP: 0010:__validate_creds include/linux/cred.h:187 [inline]
RIP: 0010:override_creds+0x9f/0x170 kernel/cred.c:550
Code: ac 25 00 81 fb 64 65 73 43 0f 85 a3 37 00 00 e8 17 ab 25 00 49 8d 7c 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 96 00 00 00 41 8b 5c 24 10 bf
RSP: 0018:ffff88809c45fda0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000043736564 RCX: ffffffff814f3318
RDX: 0000000000000002 RSI: ffffffff814f3329 RDI: 0000000000000010
RBP: ffff88809c45fdb8 R08: ffff8880a3aac240 R09: ffffed1014755849
R10: ffffed1014755848 R11: ffff8880a3aac247 R12: 0000000000000000
R13: ffff888098ab1600 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd51c40664 CR3: 0000000092641000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 io_sq_thread+0x1c7/0xa20 fs/io_uring.c:3274
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace f2e1a4307fbe2245 ]---
RIP: 0010:creds_are_invalid kernel/cred.c:792 [inline]
RIP: 0010:__validate_creds include/linux/cred.h:187 [inline]
RIP: 0010:override_creds+0x9f/0x170 kernel/cred.c:550
Code: ac 25 00 81 fb 64 65 73 43 0f 85 a3 37 00 00 e8 17 ab 25 00 49 8d 7c 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 96 00 00 00 41 8b 5c 24 10 bf
RSP: 0018:ffff88809c45fda0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000043736564 RCX: ffffffff814f3318
RDX: 0000000000000002 RSI: ffffffff814f3329 RDI: 0000000000000010
RBP: ffff88809c45fdb8 R08: ffff8880a3aac240 R09: ffffed1014755849
R10: ffffed1014755848 R11: ffff8880a3aac247 R12: 0000000000000000
R13: ffff888098ab1600 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd51c40664 CR3: 0000000092641000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/12/02 01:53 upstream b94ae8ad9fe7 f879db37 .config console log report syz C ci-upstream-kasan-gce-root
2019/12/05 11:07 upstream aedc0650f913 b2088328 .config console log report ci-upstream-kasan-gce-root
2019/12/04 01:27 upstream 76bb8b05960c ae13a849 .config console log report ci-upstream-kasan-gce-selinux-root
2019/12/02 00:51 upstream b94ae8ad9fe7 f879db37 .config console log report ci-upstream-kasan-gce-root
2019/12/03 19:59 linux-next 1ab75b2e415a ae13a849 .config console log report ci-upstream-linux-next-kasan-gce-root
2019/12/03 05:25 linux-next c5db92909bed ab342da3 .config console log report ci-upstream-linux-next-kasan-gce-root
* Struck through repros no longer work on HEAD.