[xfs?] general protection fault in xfs_read_agf

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fcd476ea6a88 Merge tag 'urgent-rcu.2023.03.28a' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14cddb25c80000
kernel config: https://syzkaller.appspot.com/x/.config?x=d40b592130bb7abb
dashboard link: https://syzkaller.appspot.com/bug?extid=97ae784b3df6b8b1f1e0
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
CC: [djw...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org linu...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3b69024ce3a/disk-fcd476ea.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d01c27471dc7/vmlinux-fcd476ea.xz
kernel image: https://storage.googleapis.com/syzbot-assets/69a35851c371/bzImage-fcd476ea.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+97ae78...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 5275 Comm: kworker/u4:7 Not tainted 6.3.0-rc4-syzkaller-00034-gfcd476ea6a88 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/17/2023
Workqueue: xfs_iwalk-24755 xfs_pwork_work
RIP: 0010:xfs_read_agf+0x7d/0x500 fs/xfs/libxfs/xfs_alloc.c:2990
Code: 82 c7 00 f1 f1 f1 f1 c7 40 04 00 00 f3 f3 65 48 8b 04 25 28 00 00 00 48 89 44 24 78 31 c0 e8 0a 40 8c fe 48 89 d8 48 c1 e8 03 <80> 3c 28 00 0f 85 1f 04 00 00 48 8b 2b 0f 1f 44 00 00 48 8d 43 08
RSP: 0018:ffffc9000558f1b8 EFLAGS: 00010256
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88807ace3a80 RSI: ffffffff82f69846 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000094001 R12: 0000000000000000
R13: 1ffff92000ab1e3b R14: ffffc9000558f2c0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0176a9840 CR3: 0000000031d9d000 CR4: 0000000000350ee0
Call Trace:
<TASK>
xfs_alloc_read_agf+0x102/0xba0 fs/xfs/libxfs/xfs_alloc.c:3027
xfs_agfl_free_finish_item+0x253/0x6a0 fs/xfs/xfs_extfree_item.c:543
xfs_defer_finish_one fs/xfs/libxfs/xfs_defer.c:479 [inline]
xfs_defer_finish_noroll+0xa39/0x1d10 fs/xfs/libxfs/xfs_defer.c:563
__xfs_trans_commit+0x7c1/0xfa0 fs/xfs/xfs_trans.c:970
xfs_dquot_disk_alloc+0x9cf/0xb80 fs/xfs/xfs_dquot.c:384
xfs_qm_dqread+0x4dd/0x570 fs/xfs/xfs_dquot.c:665
xfs_qm_dqget+0x141/0x660 fs/xfs/xfs_dquot.c:870
xfs_qm_quotacheck_dqadjust+0xa7/0x4e0 fs/xfs/xfs_qm.c:1085
xfs_qm_dqusage_adjust+0x3e5/0x570 fs/xfs/xfs_qm.c:1190
xfs_iwalk_ag_recs+0x449/0x770 fs/xfs/xfs_iwalk.c:220
xfs_iwalk_run_callbacks+0x1fa/0x4b0 fs/xfs/xfs_iwalk.c:376
xfs_iwalk_ag+0x731/0x930 fs/xfs/xfs_iwalk.c:482
xfs_iwalk_ag_work+0x14a/0x1c0 fs/xfs/xfs_iwalk.c:624
xfs_pwork_work+0x7f/0x160 fs/xfs/xfs_pwork.c:47
process_one_work+0x991/0x15c0 kernel/workqueue.c:2390
worker_thread+0x669/0x1090 kernel/workqueue.c:2537
kthread+0x2e8/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:xfs_read_agf+0x7d/0x500 fs/xfs/libxfs/xfs_alloc.c:2990
Code: 82 c7 00 f1 f1 f1 f1 c7 40 04 00 00 f3 f3 65 48 8b 04 25 28 00 00 00 48 89 44 24 78 31 c0 e8 0a 40 8c fe 48 89 d8 48 c1 e8 03 <80> 3c 28 00 0f 85 1f 04 00 00 48 8b 2b 0f 1f 44 00 00 48 8d 43 08
RSP: 0018:ffffc9000558f1b8 EFLAGS: 00010256
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88807ace3a80 RSI: ffffffff82f69846 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000094001 R12: 0000000000000000
R13: 1ffff92000ab1e3b R14: ffffc9000558f2c0 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0176a9840 CR3: 0000000031d9d000 CR4: 0000000000350ee0
----------------
Code disassembly (best guess), 1 bytes skipped:
0: c7 00 f1 f1 f1 f1 movl $0xf1f1f1f1,(%rax)
6: c7 40 04 00 00 f3 f3 movl $0xf3f30000,0x4(%rax)
d: 65 48 8b 04 25 28 00 mov %gs:0x28,%rax
14: 00 00
16: 48 89 44 24 78 mov %rax,0x78(%rsp)
1b: 31 c0 xor %eax,%eax
1d: e8 0a 40 8c fe callq 0xfe8c402c
22: 48 89 d8 mov %rbx,%rax
25: 48 c1 e8 03 shr $0x3,%rax
* 29: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) <-- trapping instruction
2d: 0f 85 1f 04 00 00 jne 0x452
33: 48 8b 2b mov (%rbx),%rbp
36: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
3b: 48 8d 43 08 lea 0x8(%rbx),%rax


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.