syzbot


general protection fault in do_writepages

Status: premoderation: reported on 2025/02/19 08:07
Reported-by: syzbot+28fc86f9397bf570daaa@syzkaller.appspotmail.com
First crash: 4d05h, last: 4d05h

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc000000002d: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000168-0x000000000000016f]
CPU: 1 PID: 26960 Comm: kworker/u4:10 Not tainted 5.15.178-syzkaller-00193-g058abb720bd1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: writeback wb_workfn (flush-7:5)
RIP: 0010:wb_bandwidth_estimate_start mm/page-writeback.c:1411 [inline]
RIP: 0010:do_writepages+0x224/0x670 mm/page-writeback.c:2385
Code: c7 c7 80 b9 a0 86 e8 fb 33 18 00 4c 8b 2d 84 1b 06 05 48 89 5c 24 10 48 8d 83 08 01 00 00 48 89 c1 48 c1 e9 03 48 89 4c 24 28 <42> 80 3c 21 00 48 89 04 24 74 0d 48 8b 3c 24 e8 c8 33 18 00 48 8b
RSP: 0018:ffffc90000c47380 EFLAGS: 00010206
RAX: 0000000000000168 RBX: 0000000000000060 RCX: 000000000000002d
RDX: 0000000000000000 RSI: 0000000000000400 RDI: 0000000000000001
RBP: ffffc90000c47508 R08: ffffffff819a9ca2 R09: 0000000000000003
R10: fffff52000188ea0 R11: dffffc0000000001 R12: dffffc0000000000
R13: 0000000100041725 R14: ffff88813029be30 R15: ffffc90000c47730
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055557a7e94a8 CR3: 000000011b79c000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __writeback_single_inode+0xdf/0xa70 fs/fs-writeback.c:1647
 writeback_sb_inodes+0xb2a/0x1920 fs/fs-writeback.c:1930
 __writeback_inodes_wb+0x118/0x3f0 fs/fs-writeback.c:2001
 wb_writeback+0x3da/0x9f0 fs/fs-writeback.c:2108
 wb_check_old_data_flush fs/fs-writeback.c:2212 [inline]
 wb_do_writeback fs/fs-writeback.c:2265 [inline]
 wb_workfn+0xb3d/0x1110 fs/fs-writeback.c:2294
 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2325
 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2472
 kthread+0x421/0x510 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Modules linked in:
---[ end trace 1369c6bc797f4c3d ]---
RIP: 0010:wb_bandwidth_estimate_start mm/page-writeback.c:1411 [inline]
RIP: 0010:do_writepages+0x224/0x670 mm/page-writeback.c:2385
Code: c7 c7 80 b9 a0 86 e8 fb 33 18 00 4c 8b 2d 84 1b 06 05 48 89 5c 24 10 48 8d 83 08 01 00 00 48 89 c1 48 c1 e9 03 48 89 4c 24 28 <42> 80 3c 21 00 48 89 04 24 74 0d 48 8b 3c 24 e8 c8 33 18 00 48 8b
RSP: 0018:ffffc90000c47380 EFLAGS: 00010206
RAX: 0000000000000168 RBX: 0000000000000060 RCX: 000000000000002d
RDX: 0000000000000000 RSI: 0000000000000400 RDI: 0000000000000001
RBP: ffffc90000c47508 R08: ffffffff819a9ca2 R09: 0000000000000003
R10: fffff52000188ea0 R11: dffffc0000000001 R12: dffffc0000000000
R13: 0000000100041725 R14: ffff88813029be30 R15: ffffc90000c47730
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000400001000000 CR3: 0000000006a0f000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	c7 c7 80 b9 a0 86    	mov    $0x86a0b980,%edi
   6:	e8 fb 33 18 00       	call   0x183406
   b:	4c 8b 2d 84 1b 06 05 	mov    0x5061b84(%rip),%r13        # 0x5061b96
  12:	48 89 5c 24 10       	mov    %rbx,0x10(%rsp)
  17:	48 8d 83 08 01 00 00 	lea    0x108(%rbx),%rax
  1e:	48 89 c1             	mov    %rax,%rcx
  21:	48 c1 e9 03          	shr    $0x3,%rcx
  25:	48 89 4c 24 28       	mov    %rcx,0x28(%rsp)
* 2a:	42 80 3c 21 00       	cmpb   $0x0,(%rcx,%r12,1) <-- trapping instruction
  2f:	48 89 04 24          	mov    %rax,(%rsp)
  33:	74 0d                	je     0x42
  35:	48 8b 3c 24          	mov    (%rsp),%rdi
  39:	e8 c8 33 18 00       	call   0x183406
  3e:	48                   	rex.W
  3f:	8b                   	.byte 0x8b

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/19 08:06 android13-5.15-lts 058abb720bd1 9a14138f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 general protection fault in do_writepages
* Struck through repros no longer work on HEAD.