[syzbot] [netfs?] general protection fault in netfs_put_subrequest

[syzbot] [netfs?] general protection fault in netfs_put_subrequest

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    9a9c8ce300cd Merge tag 'kbuild-fixes-7.0-4' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=142de106580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5a3e5e8c17cc174e
dashboard link: https://syzkaller.appspot.com/bug?extid=a0788ffdca16ee21c493
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-9a9c8ce3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/073107a6c46a/vmlinux-9a9c8ce3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f6457493483c/bzImage-9a9c8ce3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a0788ffdca16ee21c493@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000055: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x00000000000002a8-0x00000000000002af]
CPU: 1 UID: 0 PID: 1247 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: events_unbound netfs_unbuffered_write_async

RIP: 0010:netfs_put_subrequest+0x88/0x4e0 fs/netfs/objects.c:248
Code: df 48 c1 ea 03 80 3c 02 00 0f 85 fa 03 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 2b 48 8d bd ac 02 00 00 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 96
RSP: 0018:ffffc9000619fa48 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88804679adc0 RCX: 0000000000000000
RDX: 0000000000000055 RSI: 0000000000000008 RDI: 00000000000002ac
RBP: 0000000000000000 R08: 1ffff110055b509b R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000007
R13: 0000000000000001 R14: 0000000000000002 R15: ffff88804679ae10
FS:  0000000000000000(0000) GS:ffff8880d6438000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000002b072000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 netfs_clear_subrequests+0x158/0x260 fs/netfs/objects.c:106
 netfs_unbuffered_write_done fs/netfs/direct_write.c:59 [inline]
 netfs_unbuffered_write+0x13ac/0x2260 fs/netfs/direct_write.c:202
 netfs_unbuffered_write_async+0x19/0x30 fs/netfs/direct_write.c:211
 process_one_work+0xa23/0x19a0 kernel/workqueue.c:3276
 process_scheduled_works kernel/workqueue.c:3359 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3440
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:netfs_put_subrequest+0x88/0x4e0 fs/netfs/objects.c:248
Code: df 48 c1 ea 03 80 3c 02 00 0f 85 fa 03 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 2b 48 8d bd ac 02 00 00 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 96
RSP: 0018:ffffc9000619fa48 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: ffff88804679adc0 RCX: 0000000000000000
RDX: 0000000000000055 RSI: 0000000000000008 RDI: 00000000000002ac
RBP: 0000000000000000 R08: 1ffff110055b509b R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000007
R13: 0000000000000001 R14: 0000000000000002 R15: ffff88804679ae10
FS:  0000000000000000(0000) GS:ffff8880d6438000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000031877000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	48 c1 ea 03          	shr    $0x3,%rdx
   4:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   8:	0f 85 fa 03 00 00    	jne    0x408
   e:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  15:	fc ff df
  18:	48 8b 2b             	mov    (%rbx),%rbp
  1b:	48 8d bd ac 02 00 00 	lea    0x2ac(%rbp),%rdi
  22:	48 89 fa             	mov    %rdi,%rdx
  25:	48 c1 ea 03          	shr    $0x3,%rdx
* 29:	0f b6 14 02          	movzbl (%rdx,%rax,1),%edx <-- trapping instruction
  2d:	48 89 f8             	mov    %rdi,%rax
  30:	83 e0 07             	and    $0x7,%eax
  33:	83 c0 03             	add    $0x3,%eax
  36:	38 d0                	cmp    %dl,%al
  38:	7c 08                	jl     0x42
  3a:	84 d2                	test   %dl,%dl
  3c:	0f                   	.byte 0xf
  3d:	85                   	.byte 0x85
  3e:	96                   	xchg   %eax,%esi


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