[syzbot] [mm?] [gfs2?] WARNING in read_rindex_entry

[syzbot] [mm?] [gfs2?] WARNING in read_rindex_entry

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    15ef2f78c49d Merge tag 'input-for-v7.2-rc7' of git://git.k..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10871279580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a0fdc3b566746377
dashboard link: https://syzkaller.appspot.com/bug?extid=9d20c3ad7d29227de28d
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14871279580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=100d2a25580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c2a8c7d3a889/disk-15ef2f78.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2da78afed345/vmlinux-15ef2f78.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c4ffd97e4708/bzImage-15ef2f78.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/eaa4120812b6/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=17f52a25580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com

gfs2: fsid=.: Now mounting FS (format 1801)...
gfs2: fsid=..0: journal 0 mapped with 18 extents in 0ms
gfs2: fsid=..0: first mount done, others may mount
------------[ cut here ]------------
1
WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x2427/0x2dc0 mm/page_alloc.c:5280, CPU#1: syz-executor256/5629
Modules linked in:
CPU: 1 UID: 0 PID: 5629 Comm: syz-executor256 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:__alloc_frozen_pages_noprof+0x2427/0x2dc0 mm/page_alloc.c:5280
Code: e9 8d fb ff ff 31 d2 be 28 12 00 00 48 c7 c7 a0 64 e1 8b e8 5b 8c 69 ff 2e 2e 2e 31 c0 e9 02 ed ff ff c6 05 54 c1 9d 0e 01 90 <0f> 0b 90 e9 6f df ff ff 48 c7 c7 80 ae d3 8e 45 89 f7 44 8b 74 24
RSP: 0018:ffffc9000345f0e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 1ffff9200068be36 RDI: 0000000000040d40
RBP: 000000000000000b R08: 0000000000000005 R09: 0000000000000009
R10: 000000000000000b R11: 0000000000000000 R12: 0000000000040d40
R13: 1ffff9200068be74 R14: ffffffff9b759444 R15: 0000000000000001
FS:  000055556d263400(0000) GS:ffff888123ee1000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055886dbe9978 CR3: 000000003394d000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2490
 ___kmalloc_large_node+0xe5/0x120 mm/slub.c:5274
 __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:5305
 __do_kmalloc_node mm/slub.c:5322 [inline]
 __kmalloc_noprof+0x5a1/0x820 mm/slub.c:5359
 _kmalloc_noprof include/linux/slab.h:992 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 compute_bitstructs fs/gfs2/rgrp.c:766 [inline]
 read_rindex_entry+0x4a1/0x1250 fs/gfs2/rgrp.c:931
 gfs2_ri_update+0x6f/0x3b0 fs/gfs2/rgrp.c:1001
 gfs2_rindex_update+0x40b/0x480 fs/gfs2/rgrp.c:1051
 init_inodes+0x1f78/0x2790 fs/gfs2/ops_fstype.c:872
 gfs2_fill_super+0x1d3d/0x2cf0 fs/gfs2/ops_fstype.c:1250
 get_tree_bdev_flags+0x38c/0x620 fs/super.c:1640
 gfs2_get_tree+0x4e/0x280 fs/gfs2/ops_fstype.c:1332
 vfs_get_tree+0x92/0x320 fs/super.c:1700
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount fs/namespace.c:3841 [inline]
 path_mount+0x7d0/0x23d0 fs/namespace.c:4161
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount fs/namespace.c:4367 [inline]
 __x64_sys_mount+0x293/0x310 fs/namespace.c:4367
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff9e8de99ea
Code: 56 53 b8 9d 00 00 00 0f 05 83 f8 ea 75 a2 c7 05 a4 30 0a 00 00 00 00 00 eb 96 e8 51 05 00 00 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc770eecc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc770eece0 RCX: 00007ff9e8de99ea
RDX: 0000200000000040 RSI: 0000200000000100 RDI: 00007ffc770eece0
RBP: 0000200000000100 R08: 00007ffc770eed20 R09: 0000000000000000
R10: 0000000000008cd3 R11: 0000000000000246 R12: 0000200000000040
R13: 0000000000000004 R14: 0000000000000003 R15: 00007ffc770eed20
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
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If the report is already addressed, 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
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
#syz undup

Re: [syzbot] [mm?] [gfs2?] WARNING in read_rindex_entry

[Andrew Morton]

On Wed, 19 Aug 2026 15:49:42 -0700 syzbot <syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com> wrote:

> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    15ef2f78c49d Merge tag 'input-for-v7.2-rc7' of git://git.k..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=10871279580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a0fdc3b566746377
> dashboard link: https://syzkaller.appspot.com/bug?extid=9d20c3ad7d29227de28d
> compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14871279580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=100d2a25580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/c2a8c7d3a889/disk-15ef2f78.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/2da78afed345/vmlinux-15ef2f78.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/c4ffd97e4708/bzImage-15ef2f78.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/eaa4120812b6/mount_0.gz
>   fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=17f52a25580000)
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com

Thanks.  Mounting an intentionally corrupted fs image, I assume.

It appears that GFS2 forgot to validate the `ri_length' which it read
from disk.  That gets used in compute_bitstructs()->kzalloc_objs() and
the memory allocator didn't like the excessively-sized allocation
attempt.

> gfs2: fsid=.: Now mounting FS (format 1801)...
> gfs2: fsid=..0: journal 0 mapped with 18 extents in 0ms
> gfs2: fsid=..0: first mount done, others may mount
> ------------[ cut here ]------------
> 1
> WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x2427/0x2dc0 mm/page_alloc.c:5280, CPU#1: syz-executor256/5629
> Modules linked in:
> CPU: 1 UID: 0 PID: 5629 Comm: syz-executor256 Not tainted syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
> RIP: 0010:__alloc_frozen_pages_noprof+0x2427/0x2dc0 mm/page_alloc.c:5280
> Code: e9 8d fb ff ff 31 d2 be 28 12 00 00 48 c7 c7 a0 64 e1 8b e8 5b 8c 69 ff 2e 2e 2e 31 c0 e9 02 ed ff ff c6 05 54 c1 9d 0e 01 90 <0f> 0b 90 e9 6f df ff ff 48 c7 c7 80 ae d3 8e 45 89 f7 44 8b 74 24
> RSP: 0018:ffffc9000345f0e0 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: 1ffff9200068be36 RDI: 0000000000040d40
> RBP: 000000000000000b R08: 0000000000000005 R09: 0000000000000009
> R10: 000000000000000b R11: 0000000000000000 R12: 0000000000040d40
> R13: 1ffff9200068be74 R14: ffffffff9b759444 R15: 0000000000000001
> FS:  000055556d263400(0000) GS:ffff888123ee1000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 000055886dbe9978 CR3: 000000003394d000 CR4: 0000000000350ef0
> Call Trace:
>  <TASK>
>  alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2490
>  ___kmalloc_large_node+0xe5/0x120 mm/slub.c:5274
>  __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:5305
>  __do_kmalloc_node mm/slub.c:5322 [inline]
>  __kmalloc_noprof+0x5a1/0x820 mm/slub.c:5359
>  _kmalloc_noprof include/linux/slab.h:992 [inline]
>  _kzalloc_noprof include/linux/slab.h:1309 [inline]
>  compute_bitstructs fs/gfs2/rgrp.c:766 [inline]
>  read_rindex_entry+0x4a1/0x1250 fs/gfs2/rgrp.c:931
>  gfs2_ri_update+0x6f/0x3b0 fs/gfs2/rgrp.c:1001
>  gfs2_rindex_update+0x40b/0x480 fs/gfs2/rgrp.c:1051
>  init_inodes+0x1f78/0x2790 fs/gfs2/ops_fstype.c:872
>  gfs2_fill_super+0x1d3d/0x2cf0 fs/gfs2/ops_fstype.c:1250
>  get_tree_bdev_flags+0x38c/0x620 fs/super.c:1640
>  gfs2_get_tree+0x4e/0x280 fs/gfs2/ops_fstype.c:1332
>  vfs_get_tree+0x92/0x320 fs/super.c:1700
>  fc_mount fs/namespace.c:1198 [inline]
>  do_new_mount_fc fs/namespace.c:3765 [inline]
>  do_new_mount fs/namespace.c:3841 [inline]
>  path_mount+0x7d0/0x23d0 fs/namespace.c:4161
>  do_mount fs/namespace.c:4174 [inline]
>  __do_sys_mount fs/namespace.c:4390 [inline]
>  __se_sys_mount fs/namespace.c:4367 [inline]
>  __x64_sys_mount+0x293/0x310 fs/namespace.c:4367
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7ff9e8de99ea
> Code: 56 53 b8 9d 00 00 00 0f 05 83 f8 ea 75 a2 c7 05 a4 30 0a 00 00 00 00 00 eb 96 e8 51 05 00 00 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 d8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffc770eecc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007ffc770eece0 RCX: 00007ff9e8de99ea
> RDX: 0000200000000040 RSI: 0000200000000100 RDI: 00007ffc770eece0
> RBP: 0000200000000100 R08: 00007ffc770eed20 R09: 0000000000000000
> R10: 0000000000008cd3 R11: 0000000000000246 R12: 0000200000000040
> R13: 0000000000000004 R14: 0000000000000003 R15: 00007ffc770eed20
>  </TASK>
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, 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
> If you attach or paste a git patch, syzbot will apply it before testing.
> 
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup

Re: [syzbot] [mm?] [gfs2?] WARNING in read_rindex_entry

[Zi Yan]

On Wed Aug 19, 2026 at 8:14 PM EDT, Andrew Morton wrote:
> On Wed, 19 Aug 2026 15:49:42 -0700 syzbot <syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com> wrote:
>
>> Hello,
>> 
>> syzbot found the following issue on:
>> 
>> HEAD commit:    15ef2f78c49d Merge tag 'input-for-v7.2-rc7' of git://git.k..
>> git tree:       upstream
>> console+strace: https://syzkaller.appspot.com/x/log.txt?x=10871279580000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=a0fdc3b566746377
>> dashboard link: https://syzkaller.appspot.com/bug?extid=9d20c3ad7d29227de28d
>> compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14871279580000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=100d2a25580000
>> 
>> Downloadable assets:
>> disk image: https://storage.googleapis.com/syzbot-assets/c2a8c7d3a889/disk-15ef2f78.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/2da78afed345/vmlinux-15ef2f78.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/c4ffd97e4708/bzImage-15ef2f78.xz
>> mounted in repro: https://storage.googleapis.com/syzbot-assets/eaa4120812b6/mount_0.gz
>>   fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=17f52a25580000)
>> 
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com
>
> Thanks.  Mounting an intentionally corrupted fs image, I assume.
>
> It appears that GFS2 forgot to validate the `ri_length' which it read
> from disk.  That gets used in compute_bitstructs()->kzalloc_objs() and
> the memory allocator didn't like the excessively-sized allocation
> attempt.

+Vlastimil

This makes me question my recent patch[1] that returns NULL for kmalloc
sizes bigger than KMALLOC_MAX_SIZE. It masks this issue.

Probably, we should use __GFP_NOWARN for the GadgetFS warn[2] like
Andrew suggested, since the caller does not care the NULL from kmalloc()
is caused by invalid input or ENOMEM.

For this one, GFS2 needs to validate the ri_length.


[1] https://lore.kernel.org/all/20260817-limit_kmalloc_size-v1-1-5bef487701cc@nvidia.com/
[2] https://lore.kernel.org/all/6a820ebc.9ebadd4d.20b15e.001b.GAE@google.com/
>
>> gfs2: fsid=.: Now mounting FS (format 1801)...
>> gfs2: fsid=..0: journal 0 mapped with 18 extents in 0ms
>> gfs2: fsid=..0: first mount done, others may mount
>> ------------[ cut here ]------------
>> 1
>> WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x2427/0x2dc0 mm/page_alloc.c:5280, CPU#1: syz-executor256/5629
>> Modules linked in:
>> CPU: 1 UID: 0 PID: 5629 Comm: syz-executor256 Not tainted syzkaller #0 PREEMPT(full) 
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
>> RIP: 0010:__alloc_frozen_pages_noprof+0x2427/0x2dc0 mm/page_alloc.c:5280
>> Code: e9 8d fb ff ff 31 d2 be 28 12 00 00 48 c7 c7 a0 64 e1 8b e8 5b 8c 69 ff 2e 2e 2e 31 c0 e9 02 ed ff ff c6 05 54 c1 9d 0e 01 90 <0f> 0b 90 e9 6f df ff ff 48 c7 c7 80 ae d3 8e 45 89 f7 44 8b 74 24
>> RSP: 0018:ffffc9000345f0e0 EFLAGS: 00010246
>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
>> RDX: 0000000000000000 RSI: 1ffff9200068be36 RDI: 0000000000040d40
>> RBP: 000000000000000b R08: 0000000000000005 R09: 0000000000000009
>> R10: 000000000000000b R11: 0000000000000000 R12: 0000000000040d40
>> R13: 1ffff9200068be74 R14: ffffffff9b759444 R15: 0000000000000001
>> FS:  000055556d263400(0000) GS:ffff888123ee1000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 000055886dbe9978 CR3: 000000003394d000 CR4: 0000000000350ef0
>> Call Trace:
>>  <TASK>
>>  alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2490
>>  ___kmalloc_large_node+0xe5/0x120 mm/slub.c:5274
>>  __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:5305
>>  __do_kmalloc_node mm/slub.c:5322 [inline]
>>  __kmalloc_noprof+0x5a1/0x820 mm/slub.c:5359
>>  _kmalloc_noprof include/linux/slab.h:992 [inline]
>>  _kzalloc_noprof include/linux/slab.h:1309 [inline]
>>  compute_bitstructs fs/gfs2/rgrp.c:766 [inline]
>>  read_rindex_entry+0x4a1/0x1250 fs/gfs2/rgrp.c:931
>>  gfs2_ri_update+0x6f/0x3b0 fs/gfs2/rgrp.c:1001
>>  gfs2_rindex_update+0x40b/0x480 fs/gfs2/rgrp.c:1051
>>  init_inodes+0x1f78/0x2790 fs/gfs2/ops_fstype.c:872
>>  gfs2_fill_super+0x1d3d/0x2cf0 fs/gfs2/ops_fstype.c:1250
>>  get_tree_bdev_flags+0x38c/0x620 fs/super.c:1640
>>  gfs2_get_tree+0x4e/0x280 fs/gfs2/ops_fstype.c:1332
>>  vfs_get_tree+0x92/0x320 fs/super.c:1700
>>  fc_mount fs/namespace.c:1198 [inline]
>>  do_new_mount_fc fs/namespace.c:3765 [inline]
>>  do_new_mount fs/namespace.c:3841 [inline]
>>  path_mount+0x7d0/0x23d0 fs/namespace.c:4161
>>  do_mount fs/namespace.c:4174 [inline]
>>  __do_sys_mount fs/namespace.c:4390 [inline]
>>  __se_sys_mount fs/namespace.c:4367 [inline]
>>  __x64_sys_mount+0x293/0x310 fs/namespace.c:4367
>>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>>  do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
>>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> RIP: 0033:0x7ff9e8de99ea
>> Code: 56 53 b8 9d 00 00 00 0f 05 83 f8 ea 75 a2 c7 05 a4 30 0a 00 00 00 00 00 eb 96 e8 51 05 00 00 90 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 d8 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007ffc770eecc8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
>> RAX: ffffffffffffffda RBX: 00007ffc770eece0 RCX: 00007ff9e8de99ea
>> RDX: 0000200000000040 RSI: 0000200000000100 RDI: 00007ffc770eece0
>> RBP: 0000200000000100 R08: 00007ffc770eed20 R09: 0000000000000000
>> R10: 0000000000008cd3 R11: 0000000000000246 R12: 0000200000000040
>> R13: 0000000000000004 R14: 0000000000000003 R15: 00007ffc770eed20
>>  </TASK>
>> 
>> 
>> ---
>> This report is generated by a bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for more information about syzbot.
>> syzbot engineers can be reached at syzkaller@googlegroups.com.
>> 
>> syzbot will keep track of this issue. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>> 
>> If the report is already addressed, 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
>> If you attach or paste a git patch, syzbot will apply it before testing.
>> 
>> If you want to overwrite report's subsystems, reply with:
>> #syz set subsystems: new-subsystem
>> (See the list of subsystem names on the web dashboard)
>> 
>> If the report is a duplicate of another one, reply with:
>> #syz dup: exact-subject-of-another-report
>> 
>> If you want to undo deduplication, reply with:
>> #syz undup




-- 
Best Regards,
Yan, Zi

[PATCH] gfs2: valid the length of rgrp header

[Edward Adam Davis]

When mounting a deliberately corrupted filesystem image, an excessively
large rgrp header length is used in a call to kzalloc_objs() within
compute_bitstructs(), and the memory allocator cannot handle such a large
allocation request. This triggers [1].

Add a check for the rgrp header length to avoid [1].

[1]
WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x2427/0x2dc0 mm/page_alloc.c:5280, CPU#1: syz-executor256/5629
Call Trace:
 alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2490
 ___kmalloc_large_node+0xe5/0x120 mm/slub.c:5274
 __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:5305
 __do_kmalloc_node mm/slub.c:5322 [inline]
 __kmalloc_noprof+0x5a1/0x820 mm/slub.c:5359
 _kmalloc_noprof include/linux/slab.h:992 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 compute_bitstructs fs/gfs2/rgrp.c:766 [inline]
 read_rindex_entry+0x4a1/0x1250 fs/gfs2/rgrp.c:931
 gfs2_ri_update+0x6f/0x3b0 fs/gfs2/rgrp.c:1001
 gfs2_rindex_update+0x40b/0x480 fs/gfs2/rgrp.c:1051
 init_inodes+0x1f78/0x2790 fs/gfs2/ops_fstype.c:872
 gfs2_fill_super+0x1d3d/0x2cf0 fs/gfs2/ops_fstype.c:1250
 get_tree_bdev_flags+0x38c/0x620 fs/super.c:1640
 gfs2_get_tree+0x4e/0x280 fs/gfs2/ops_fstype.c:1332
 vfs_get_tree+0x92/0x320 fs/super.c:1700
 fc_mount fs/namespace.c:1198 [inline]

Fixes: bb8d8a6f54c1 ("[GFS2] Fix sign problem in quota/statfs and cleanup _host structures")
Reported-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9d20c3ad7d29227de28d
Tested-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/gfs2/rgrp.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 5988a165a830..53d097ce668e 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -899,6 +899,7 @@ static int read_rindex_entry(struct gfs2_inode *ip)
 	struct gfs2_rindex buf;
 	int error;
 	struct gfs2_rgrpd *rgd;
+	size_t size;
 
 	if (pos >= i_size_read(&ip->i_inode))
 		return 1;
@@ -917,6 +918,13 @@ static int read_rindex_entry(struct gfs2_inode *ip)
 	rgd->rd_sbd = sdp;
 	rgd->rd_addr = be64_to_cpu(buf.ri_addr);
 	rgd->rd_length = be32_to_cpu(buf.ri_length);
+
+	size = rgd->rd_length * sizeof(struct gfs2_bitmap);
+	if (get_order(size) > MAX_PAGE_ORDER) {
+		error = -EINVAL;
+		goto fail;
+	}
+
 	rgd->rd_data0 = be64_to_cpu(buf.ri_data0);
 	rgd->rd_data = be32_to_cpu(buf.ri_data);
 	rgd->rd_bitbytes = be32_to_cpu(buf.ri_bitbytes);
-- 
2.43.0

Re: [syzbot] [mm?] [gfs2?] WARNING in read_rindex_entry

[Andreas Gruenbacher]

On Thu, Aug 20, 2026 at 2:24 AM Andrew Morton <akpm@linux-foundation.org> wrote:
> On Wed, 19 Aug 2026 15:49:42 -0700 syzbot <syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com> wrote:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    15ef2f78c49d Merge tag 'input-for-v7.2-rc7' of git://git.k..
> > git tree:       upstream
> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=10871279580000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=a0fdc3b566746377
> > dashboard link: https://syzkaller.appspot.com/bug?extid=9d20c3ad7d29227de28d
> > compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14871279580000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=100d2a25580000
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/c2a8c7d3a889/disk-15ef2f78.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/2da78afed345/vmlinux-15ef2f78.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/c4ffd97e4708/bzImage-15ef2f78.xz
> > mounted in repro: https://storage.googleapis.com/syzbot-assets/eaa4120812b6/mount_0.gz
> >   fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=17f52a25580000)
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com
>
> Thanks.  Mounting an intentionally corrupted fs image, I assume.
>
> It appears that GFS2 forgot to validate the `ri_length' which it read
> from disk.  That gets used in compute_bitstructs()->kzalloc_objs() and
> the memory allocator didn't like the excessively-sized allocation
> attempt.

Thanks for looking into this.  This commit (attached below) from the
for-later branch should prevent that from happening:

https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/8684#note_3716004816

Thanks,
Andreas

--

gfs2: Improve resource group validation and error handling

Validate the resource group boundaries, check against the device size, simplify
the initialization logic, and check for resource group overlaps.

Reported-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9d20c3ad7d29227de28d
Tested-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/gfs2/rgrp.c | 123 ++++++++++++++++++++++++++-----------------------
 1 file changed, 65 insertions(+), 58 deletions(-)

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index f6048a73e5c3..3ac751eea055 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -745,6 +745,7 @@ void gfs2_clear_rgrpd(struct gfs2_sbd *sdp)
 
 /**
  * compute_bitstructs - Compute the bitmap sizes
+ * @sb: The superblock
  * @rgd: The resource group descriptor
  *
  * Calculates bitmap descriptors, one for each block that contains bitmap data
@@ -752,84 +753,74 @@ void gfs2_clear_rgrpd(struct gfs2_sbd *sdp)
  * Returns: errno
  */
 
-static int compute_bitstructs(struct gfs2_rgrpd *rgd)
+static int compute_bitstructs(struct super_block *sb, struct gfs2_rgrpd *rgd)
 {
 	struct gfs2_sbd *sdp = rgd->rd_sbd;
 	struct gfs2_bitmap *bi;
-	u32 length = rgd->rd_length; /* # blocks in hdr & bitmap */
+	u32 expected_length;
 	u32 bytes_left, bytes;
+	u64 data_end;
 	int x;
 
-	if (!length)
-		return -EINVAL;
+	/*
+	 * The first resource group block has a gfs2_rgrp header; the remaining
+	 * blocks have a gfs2_meta_header header.  The rest of each block is
+	 * filled with bitmap data.
+	 */
+
+	if (rgd->rd_addr <= (GFS2_SB_ADDR >> sdp->sd_fsb2bb_shift)) {
+		gfs2_consist_rgrpd(rgd);
+		return -EIO;
+	}
+	if (check_add_overflow(rgd->rd_data0, rgd->rd_data, &data_end) ||
+	    rgd->rd_data == 0 || data_end > sb_bdev_nr_blocks(sb)) {
+		gfs2_consist_rgrpd(rgd);
+		return -EIO;
+	}
+	if (rgd->rd_bitbytes != DIV_ROUND_UP(rgd->rd_data, GFS2_NBBY)) {
+		gfs2_consist_rgrpd(rgd);
+		return -EIO;
+	}
+	expected_length = DIV_ROUND_UP(rgd->rd_bitbytes +
+		sizeof(struct gfs2_rgrp) - sizeof(struct gfs2_meta_header),
+		sdp->sd_sb.sb_bsize - sizeof(struct gfs2_meta_header));
+	if (rgd->rd_length != expected_length) {
+		gfs2_consist_rgrpd(rgd);
+		return -EIO;
+	}
+	if (rgd->rd_data0 < rgd->rd_addr + rgd->rd_length) {
+		gfs2_consist_rgrpd(rgd);
+		return -EIO;
+	}
 
-	rgd->rd_bits = kzalloc_objs(struct gfs2_bitmap, length, GFP_NOFS);
+	rgd->rd_bits = kzalloc_objs(struct gfs2_bitmap, rgd->rd_length, GFP_NOFS);
 	if (!rgd->rd_bits)
 		return -ENOMEM;
 
 	bytes_left = rgd->rd_bitbytes;
 
-	for (x = 0; x < length; x++) {
+	for (x = 0; x < rgd->rd_length; x++) {
 		bi = rgd->rd_bits + x;
 
 		bi->bi_flags = 0;
-		/* small rgrp; bitmap stored completely in header block */
-		if (length == 1) {
-			bytes = bytes_left;
-			bi->bi_offset = sizeof(struct gfs2_rgrp);
+		if (x == 0) {
+			/* header block */
 			bi->bi_start = 0;
-			bi->bi_bytes = bytes;
-			bi->bi_blocks = bytes * GFS2_NBBY;
-		/* header block */
-		} else if (x == 0) {
-			bytes = sdp->sd_sb.sb_bsize - sizeof(struct gfs2_rgrp);
 			bi->bi_offset = sizeof(struct gfs2_rgrp);
-			bi->bi_start = 0;
-			bi->bi_bytes = bytes;
-			bi->bi_blocks = bytes * GFS2_NBBY;
-		/* last block */
-		} else if (x + 1 == length) {
-			bytes = bytes_left;
-			bi->bi_offset = sizeof(struct gfs2_meta_header);
-			bi->bi_start = rgd->rd_bitbytes - bytes_left;
-			bi->bi_bytes = bytes;
-			bi->bi_blocks = bytes * GFS2_NBBY;
-		/* other blocks */
 		} else {
-			bytes = sdp->sd_sb.sb_bsize -
-				sizeof(struct gfs2_meta_header);
+			/* bitmap-only block */
+			struct gfs2_bitmap *prev = bi - 1;
+
+			bi->bi_start = prev->bi_start + prev->bi_bytes;
 			bi->bi_offset = sizeof(struct gfs2_meta_header);
-			bi->bi_start = rgd->rd_bitbytes - bytes_left;
-			bi->bi_bytes = bytes;
-			bi->bi_blocks = bytes * GFS2_NBBY;
 		}
-
+		bytes = sdp->sd_sb.sb_bsize - bi->bi_offset;
+		if (bytes > bytes_left)
+			bytes = bytes_left;
+		bi->bi_bytes = bytes;
+		bi->bi_blocks = bytes * GFS2_NBBY;
 		bytes_left -= bytes;
 	}
-
-	if (bytes_left) {
-		gfs2_consist_rgrpd(rgd);
-		return -EIO;
-	}
-	bi = rgd->rd_bits + (length - 1);
-	if ((bi->bi_start + bi->bi_bytes) * GFS2_NBBY != rgd->rd_data) {
-		gfs2_lm(sdp,
-			"ri_addr=%llu "
-			"ri_length=%u "
-			"ri_data0=%llu "
-			"ri_data=%u "
-			"ri_bitbytes=%u "
-			"start=%u len=%u offset=%u\n",
-			(unsigned long long)rgd->rd_addr,
-			rgd->rd_length,
-			(unsigned long long)rgd->rd_data0,
-			rgd->rd_data,
-			rgd->rd_bitbytes,
-			bi->bi_start, bi->bi_bytes, bi->bi_offset);
-		gfs2_consist_rgrpd(rgd);
-		return -EIO;
-	}
-
 	return 0;
 }
 
@@ -864,6 +855,7 @@ static int rgd_insert(struct gfs2_rgrpd *rgd)
 {
 	struct gfs2_sbd *sdp = rgd->rd_sbd;
 	struct rb_node **newn = &sdp->sd_rindex_tree.rb_node, *parent = NULL;
+	struct rb_node *prevn;
 
 	/* Figure out where to put new node */
 	while (*newn) {
@@ -882,6 +874,19 @@ static int rgd_insert(struct gfs2_rgrpd *rgd)
 	rb_link_node(&rgd->rd_node, parent, newn);
 	rb_insert_color(&rgd->rd_node, &sdp->sd_rindex_tree);
 	sdp->sd_rgrps++;
+
+	prevn = rb_prev(&rgd->rd_node);
+	if (prevn) {
+		struct gfs2_rgrpd *prev =
+			rb_entry(prevn, struct gfs2_rgrpd, rd_node);
+
+		if (prev->rd_data0 + prev->rd_data > rgd->rd_addr) {
+			fs_err(sdp, "overlapping resource groups.\n");
+			rb_erase(&rgd->rd_node, &sdp->sd_rindex_tree);
+			return -ENOENT;
+		}
+	}
+
 	return 0;
 }
 
@@ -928,7 +933,7 @@ static int read_rindex_entry(struct gfs2_inode *ip)
 	if (error)
 		goto fail;
 
-	error = compute_bitstructs(rgd);
+	error = compute_bitstructs(sdp->sd_vfs, rgd);
 	if (error)
 		goto fail_glock;
 
@@ -944,7 +949,9 @@ static int read_rindex_entry(struct gfs2_inode *ip)
 		return 0;
 	}
 
-	error = 0; /* someone else read in the rgrp; free it and ignore it */
+	/* If someone else read in the rgrp, free it and ignore it. */
+	if (error == -EEXIST)
+		error = 0;
 fail_glock:
 	gfs2_glock_put(rgd->rd_gl);
 
-- 
2.55.0

Re: [PATCH] gfs2: valid the length of rgrp header

[Andreas Gruenbacher]

On Thu, Aug 20, 2026 at 6:37 AM Edward Adam Davis <eadavis@qq.com> wrote:
> When mounting a deliberately corrupted filesystem image, an excessively
> large rgrp header length is used in a call to kzalloc_objs() within
> compute_bitstructs(), and the memory allocator cannot handle such a large
> allocation request. This triggers [1].
>
> Add a check for the rgrp header length to avoid [1].
>
> [1]
> WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x2427/0x2dc0 mm/page_alloc.c:5280, CPU#1: syz-executor256/5629
> Call Trace:
>  alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2490
>  ___kmalloc_large_node+0xe5/0x120 mm/slub.c:5274
>  __kmalloc_large_node_noprof+0x1c/0x70 mm/slub.c:5305
>  __do_kmalloc_node mm/slub.c:5322 [inline]
>  __kmalloc_noprof+0x5a1/0x820 mm/slub.c:5359
>  _kmalloc_noprof include/linux/slab.h:992 [inline]
>  _kzalloc_noprof include/linux/slab.h:1309 [inline]
>  compute_bitstructs fs/gfs2/rgrp.c:766 [inline]
>  read_rindex_entry+0x4a1/0x1250 fs/gfs2/rgrp.c:931
>  gfs2_ri_update+0x6f/0x3b0 fs/gfs2/rgrp.c:1001
>  gfs2_rindex_update+0x40b/0x480 fs/gfs2/rgrp.c:1051
>  init_inodes+0x1f78/0x2790 fs/gfs2/ops_fstype.c:872
>  gfs2_fill_super+0x1d3d/0x2cf0 fs/gfs2/ops_fstype.c:1250
>  get_tree_bdev_flags+0x38c/0x620 fs/super.c:1640
>  gfs2_get_tree+0x4e/0x280 fs/gfs2/ops_fstype.c:1332
>  vfs_get_tree+0x92/0x320 fs/super.c:1700
>  fc_mount fs/namespace.c:1198 [inline]
>
> Fixes: bb8d8a6f54c1 ("[GFS2] Fix sign problem in quota/statfs and cleanup _host structures")
> Reported-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=9d20c3ad7d29227de28d
> Tested-by: syzbot+9d20c3ad7d29227de28d@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
>  fs/gfs2/rgrp.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
> index 5988a165a830..53d097ce668e 100644
> --- a/fs/gfs2/rgrp.c
> +++ b/fs/gfs2/rgrp.c
> @@ -899,6 +899,7 @@ static int read_rindex_entry(struct gfs2_inode *ip)
>         struct gfs2_rindex buf;
>         int error;
>         struct gfs2_rgrpd *rgd;
> +       size_t size;
>
>         if (pos >= i_size_read(&ip->i_inode))
>                 return 1;
> @@ -917,6 +918,13 @@ static int read_rindex_entry(struct gfs2_inode *ip)
>         rgd->rd_sbd = sdp;
>         rgd->rd_addr = be64_to_cpu(buf.ri_addr);
>         rgd->rd_length = be32_to_cpu(buf.ri_length);
> +
> +       size = rgd->rd_length * sizeof(struct gfs2_bitmap);
> +       if (get_order(size) > MAX_PAGE_ORDER) {
> +               error = -EINVAL;
> +               goto fail;
> +       }
> +
>         rgd->rd_data0 = be64_to_cpu(buf.ri_data0);
>         rgd->rd_data = be32_to_cpu(buf.ri_data);
>         rgd->rd_bitbytes = be32_to_cpu(buf.ri_bitbytes);
> --
> 2.43.0

Thanks. The patch I've pushed to 'for-later' for validating the
resource group geometry [*] should prevent this from happening in the
first place.

[*] https://lore.kernel.org/gfs2/20260821124944.1648686-1-agruenba@redhat.com/

Andreas