syzbot


BUG: unable to handle kernel NULL pointer dereference in kiocb_done

Status: fixed on 2021/11/10 00:50
Reported-by: syzbot+726f2ce6dbbf2ad8d133@syzkaller.appspotmail.com
Fix commit: b8ce1b9d25cc io_uring: don't submit half-prepared drain request
First crash: 454d, last: 453d

Cause bisection: introduced by (bisect log) [no-op commit]:
commit a04ea6ae7c6728cd834709f3477e75d4f74583da
Author: Jason Ekstrand <jason@jlekstrand.net>
Date: Wed Jul 21 15:23:55 2021 +0000

  drm/i915: Use a table for i915_init/exit (v2)

Crash: BUG: sleeping function called from invalid context in lock_sock_nested (log)
Repro: C syz .config

Fix bisection: fixed by (bisect log) :
commit b8ce1b9d25ccf81e1bbabd45b963ed98b2222df8
Author: Pavel Begunkov <asml.silence@gmail.com>
Date: Tue Aug 31 13:13:11 2021 +0000

  io_uring: don't submit half-prepared drain request

Patch testing requests:
Created Duration User Patch Repo Result
2021/09/03 20:38 16m axboe@kernel.dk git://git.kernel.dk/linux-block for-5.15/io_uring OK

Sample crash report:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 26f41067 P4D 26f41067 PUD 17c87067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 8473 Comm: iou-wrk-8424 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc900016af910 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888036b6c000
RBP: ffff888036b6c000 R08: 0000000000000000 R09: ffff8880191787d7
R10: ffffffff81e263e4 R11: 0000000000000000 R12: 0000000000000000
R13: ffff888036b6c058 R14: ffff888036b6c040 R15: 0000000000000000
FS:  0000000002442400(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000001d9bc000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 io_rw_done fs/io_uring.c:2905 [inline]
 kiocb_done+0x1b3/0x980 fs/io_uring.c:2929
 io_read+0x3d3/0x1140 fs/io_uring.c:3503
 io_issue_sqe+0x209/0x6ba0 fs/io_uring.c:6558
 io_wq_submit_work+0x1d4/0x300 fs/io_uring.c:6707
 io_worker_handle_work+0xcb1/0x1950 fs/io-wq.c:560
 io_wqe_worker+0x2cc/0xbb0 fs/io-wq.c:609
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Modules linked in:
CR2: 0000000000000000
---[ end trace f60cb53b8a968c33 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffffc900016af910 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888036b6c000
RBP: ffff888036b6c000 R08: 0000000000000000 R09: ffff8880191787d7
R10: ffffffff81e263e4 R11: 0000000000000000 R12: 0000000000000000
R13: ffff888036b6c058 R14: ffff888036b6c040 R15: 0000000000000000
FS:  0000000002442400(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 000000001d9bc000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (3):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce 2021/09/03 04:32 upstream 4ac6d90867a4 15cea0a3 .config log report syz C BUG: unable to handle kernel NULL pointer dereference in kiocb_done
ci-upstream-kasan-gce 2021/09/03 03:57 upstream 4ac6d90867a4 15cea0a3 .config log report info BUG: unable to handle kernel NULL pointer dereference in kiocb_done
ci-upstream-kasan-gce-smack-root 2021/09/02 20:14 upstream 4ac6d90867a4 15cea0a3 .config log report info BUG: unable to handle kernel NULL pointer dereference in kiocb_done
* Struck through repros no longer work on HEAD.