[syzbot] [gfs2?] general protection fault in gfs2_lookup_simple

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a73466257270 Add linux-next specific files for 20230801
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=17a48e75a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=8b55cb25bac8948c
dashboard link: https://syzkaller.appspot.com/bug?extid=57e590d90f42e6e925df
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1263b929a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=160bbe31a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d893efe5006c/disk-a7346625.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5a2ea2e3ba30/vmlinux-a7346625.xz
kernel image: https://storage.googleapis.com/syzbot-assets/66f8ff91348f/bzImage-a7346625.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/e94e695a9f21/mount_0.gz

The issue was bisected to:

commit 8f18190e31734e434a650d3435da072f03fe485f
Author: Andreas Gruenbacher <agru...@redhat.com>
Date: Wed Jul 26 21:17:53 2023 +0000

gfs2: Use mapping->gfp_mask for metadata inodes

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1338d136a80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=10b8d136a80000
console output: https://syzkaller.appspot.com/x/log.txt?x=1738d136a80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+57e590...@syzkaller.appspotmail.com
Fixes: 8f18190e3173 ("gfs2: Use mapping->gfp_mask for metadata inodes")

gfs2: fsid=no �Šar?d: Trying to join cluster "lock_nolock", "no �Šar?d"
gfs2: fsid=no �Šar?d: Now mounting FS (format 1801)...
syz-executor418: attempt to access beyond end of device
loop0: rw=12288, sector=131072, nr_sectors = 8 limit=32768
general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
CPU: 1 PID: 5032 Comm: syz-executor418 Not tainted 6.5.0-rc4-next-20230801-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
RIP: 0010:gfs2_lookup_simple+0xc6/0x160 fs/gfs2/inode.c:286
Code: 74 24 20 f7 d0 89 44 24 20 e8 66 d3 ff ff 48 85 c0 0f 84 85 00 00 00 48 89 c3 e8 e5 01 e3 fd 48 8d 7b 30 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 75 7b 48 b8 00 00 00 00 00 fc ff df 4c 8b 63 30 49
RSP: 0018:ffffc900039ef848 EFLAGS: 00010206
RAX: 0000000000000005 RBX: fffffffffffffffb RCX: 0000000000000000
RDX: ffff888015bf8000 RSI: ffffffff83a38d4b RDI: 000000000000002b
RBP: 1ffff9200073df09 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: ffffffff8ab99700 R14: ffff888019f94000 R15: ffff8880783f06b8
FS: 00005555558fa380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000557976244798 CR3: 0000000074978000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
init_journal fs/gfs2/ops_fstype.c:742 [inline]
init_inodes+0x495/0x2e30 fs/gfs2/ops_fstype.c:885
gfs2_fill_super+0x1a9e/0x2b10 fs/gfs2/ops_fstype.c:1248
get_tree_bdev+0x390/0x6a0 fs/super.c:1345
gfs2_get_tree+0x4e/0x280 fs/gfs2/ops_fstype.c:1333
vfs_get_tree+0x88/0x350 fs/super.c:1521
do_new_mount fs/namespace.c:3335 [inline]
path_mount+0x1492/0x1ed0 fs/namespace.c:3662
do_mount fs/namespace.c:3675 [inline]
__do_sys_mount fs/namespace.c:3884 [inline]
__se_sys_mount fs/namespace.c:3861 [inline]
__x64_sys_mount+0x293/0x310 fs/namespace.c:3861
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6d772a2c3a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff3af18918 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff3af18920 RCX: 00007f6d772a2c3a
RDX: 0000000020000000 RSI: 0000000020000040 RDI: 00007fff3af18920
RBP: 0000000000000004 R08: 00007fff3af18960 R09: 00000000000125fe
R10: 0000000000000819 R11: 0000000000000282 R12: 00007fff3af18960
R13: 0000000000000003 R14: 0000000001000000 R15: 0000000000000001
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:gfs2_lookup_simple+0xc6/0x160 fs/gfs2/inode.c:286
Code: 74 24 20 f7 d0 89 44 24 20 e8 66 d3 ff ff 48 85 c0 0f 84 85 00 00 00 48 89 c3 e8 e5 01 e3 fd 48 8d 7b 30 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 75 7b 48 b8 00 00 00 00 00 fc ff df 4c 8b 63 30 49
RSP: 0018:ffffc900039ef848 EFLAGS: 00010206
RAX: 0000000000000005 RBX: fffffffffffffffb RCX: 0000000000000000
RDX: ffff888015bf8000 RSI: ffffffff83a38d4b RDI: 000000000000002b
RBP: 1ffff9200073df09 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: dffffc0000000000
R13: ffffffff8ab99700 R14: ffff888019f94000 R15: ffff8880783f06b8
FS: 00005555558fa380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564e741eb538 CR3: 0000000074978000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 74 24 je 0x26
2: 20 f7 and %dh,%bh
4: d0 89 44 24 20 e8 rorb -0x17dfdbbc(%rcx)
a: 66 d3 ff sar %cl,%di
d: ff 48 85 decl -0x7b(%rax)
10: c0 0f 84 rorb $0x84,(%rdi)
13: 85 00 test %eax,(%rax)
15: 00 00 add %al,(%rax)
17: 48 89 c3 mov %rax,%rbx
1a: e8 e5 01 e3 fd call 0xfde30204
1f: 48 8d 7b 30 lea 0x30(%rbx),%rdi
23: 48 89 f8 mov %rdi,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2f: 75 7b jne 0xac
31: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
38: fc ff df
3b: 4c 8b 63 30 mov 0x30(%rbx),%r12
3f: 49 rex.WB


---
This report is generated by a bot. It may contain errors.
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
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#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Hillf Danton]

On Sat, 05 Aug 2023 17:38:53 -0700

> HEAD commit: a73466257270 Add linux-next specific files for 20230801
> git tree: linux-next

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=160bbe31a80000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+57e590...@syzkaller.appspotmail.com

Tested on:

commit: bdffb18b Add linux-next specific files for 20230804
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=15589f13a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=4edf5fc5e1e5446f

dashboard link: https://syzkaller.appspot.com/bug?extid=57e590d90f42e6e925df
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.
Note: testing is done by a robot and is best-effort only.

[syzbot]

> #syz fix: gfs2: Use mapping->gfp_mask for metadata inodes

Your commands are accepted, but please keep syzkall...@googlegroups.com mailing list in CC next time. It serves as a history of what happened with each bug report. Thank you.

>
> commit 9c13e911dc3cdf204e45f9f259d67c6fb9ac61b7
> Author: Andreas Gruenbacher <agru...@redhat.com>
> Date: Wed Jul 26 23:17:53 2023 +0200

>
> gfs2: Use mapping->gfp_mask for metadata inodes
>

> Set mapping->gfp mask to GFP_NOFS for all metadata inodes so that
> allocating pages in the address space of those inodes won't call back
> into the filesystem. This allows to switch back from
> find_or_create_page() to grab_cache_page() in two places.
>
> Partially reverts commit 220cca2a4f58 ("GFS2: Change truncate page
> allocation to be GFP_NOFS").
>
> Thanks to Dan Carpenter <dan.ca...@linaro.org> for pointing out a
> Smatch static checker warning.
>
> Signed-off-by: Andreas Gruenbacher <agru...@redhat.com>
>