* [PATCH v2] ocfs2: validate allocator type to prevent BUG_ON in ocfs2_block_group_search
@ 2026-01-10 5:44 Deepanshu Kartikey
2026-01-23 6:23 ` Deepanshu Kartikey
0 siblings, 1 reply; 3+ messages in thread
From: Deepanshu Kartikey @ 2026-01-10 5:44 UTC (permalink / raw)
To: mark, jlbec, joseph.qi
Cc: ocfs2-devel, linux-kernel, Deepanshu Kartikey,
syzbot+44c564a3cb08605f34a1
ocfs2_is_cluster_bitmap() checks whether an inode is the global bitmap
by comparing ip_blkno with osb->bitmap_blkno. A corrupted filesystem
can have either the superblock's bitmap_blkno field corrupted to point
to the inode allocator block, or the inode allocator's i_blkno field
corrupted to match bitmap_blkno. In either case, ocfs2_is_cluster_bitmap()
returns true for the inode allocator.
When the code later calls ocfs2_block_group_search(), it triggers
BUG_ON(ocfs2_is_cluster_bitmap(inode)) causing a kernel panic.
Call trace:
ocfs2_block_group_search+0x1c7/0x2c0 fs/ocfs2/suballoc.c:1611
ocfs2_search_chain+0x38a/0x1010 fs/ocfs2/suballoc.c:1764
ocfs2_claim_suballoc_bits+0x3a4/0x650 fs/ocfs2/suballoc.c:1978
ocfs2_claim_new_inode+0x95/0x130 fs/ocfs2/suballoc.c:2137
ocfs2_mknod_locked+0x129/0x510 fs/ocfs2/namei.c:568
ocfs2_mknod+0x5c7/0x11d0 fs/ocfs2/namei.c:802
ocfs2_create+0x136/0x170 fs/ocfs2/namei.c:852
Add validation in ocfs2_reserve_suballoc_bits() to check that the
allocator inode type matches the expected type:
- Global bitmap allocator must be the cluster bitmap
- Other allocators (inode, extent) must NOT be the cluster bitmap
This follows the existing pattern of validating OCFS2_CHAIN_FL in the
same function and uses ocfs2_error() for graceful error handling.
Reported-by: syzbot+44c564a3cb08605f34a1@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=44c564a3cb08605f34a1
Tested-by: syzbot+44c564a3cb08605f34a1@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/20260104014028.305029-1-kartikey406@gmail.com/T/ [v1]
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
---
v2: Fix commit message - ocfs2_is_cluster_bitmap() checks ip_blkno
against bitmap_blkno, not a flag (Joseph Qi)
---
fs/ocfs2/suballoc.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 8e6e5235b30c..fb72c062a8d5 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -813,6 +813,26 @@ static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
goto bail;
}
+ /*
+ * Validate allocator type matches expected bitmap type.
+ * Global bitmap must have BITMAP flag, other allocators must not.
+ * This prevents a corrupted filesystem from triggering BUG_ON
+ * in ocfs2_block_group_search() or ocfs2_cluster_group_search().
+ */
+ if (type == GLOBAL_BITMAP_SYSTEM_INODE) {
+ if (!ocfs2_is_cluster_bitmap(alloc_inode)) {
+ status = ocfs2_error(alloc_inode->i_sb,
+ "Global bitmap %llu missing bitmap flag\n",
+ (unsigned long long)le64_to_cpu(fe->i_blkno));
+ goto bail;
+ }
+ } else if (ocfs2_is_cluster_bitmap(alloc_inode)) {
+ status = ocfs2_error(alloc_inode->i_sb,
+ "Allocator %llu has invalid bitmap flag\n",
+ (unsigned long long)le64_to_cpu(fe->i_blkno));
+ goto bail;
+ }
+
free_bits = le32_to_cpu(fe->id1.bitmap1.i_total) -
le32_to_cpu(fe->id1.bitmap1.i_used);
--
2.43.0
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v2] ocfs2: validate allocator type to prevent BUG_ON in ocfs2_block_group_search
2026-01-10 5:44 [PATCH v2] ocfs2: validate allocator type to prevent BUG_ON in ocfs2_block_group_search Deepanshu Kartikey
@ 2026-01-23 6:23 ` Deepanshu Kartikey
2026-01-23 8:38 ` Joseph Qi
0 siblings, 1 reply; 3+ messages in thread
From: Deepanshu Kartikey @ 2026-01-23 6:23 UTC (permalink / raw)
To: mark, jlbec, joseph.qi
Cc: ocfs2-devel, linux-kernel, syzbot+44c564a3cb08605f34a1
On Sat, Jan 10, 2026 at 11:14 AM Deepanshu Kartikey
<kartikey406@gmail.com> wrote:
>
> ocfs2_is_cluster_bitmap() checks whether an inode is the global bitmap
> by comparing ip_blkno with osb->bitmap_blkno. A corrupted filesystem
> can have either the superblock's bitmap_blkno field corrupted to point
> to the inode allocator block, or the inode allocator's i_blkno field
> corrupted to match bitmap_blkno. In either case, ocfs2_is_cluster_bitmap()
> returns true for the inode allocator.
>
> When the code later calls ocfs2_block_group_search(), it triggers
> BUG_ON(ocfs2_is_cluster_bitmap(inode)) causing a kernel panic.
>
> Call trace:
> ocfs2_block_group_search+0x1c7/0x2c0 fs/ocfs2/suballoc.c:1611
> ocfs2_search_chain+0x38a/0x1010 fs/ocfs2/suballoc.c:1764
> ocfs2_claim_suballoc_bits+0x3a4/0x650 fs/ocfs2/suballoc.c:1978
> ocfs2_claim_new_inode+0x95/0x130 fs/ocfs2/suballoc.c:2137
> ocfs2_mknod_locked+0x129/0x510 fs/ocfs2/namei.c:568
> ocfs2_mknod+0x5c7/0x11d0 fs/ocfs2/namei.c:802
> ocfs2_create+0x136/0x170 fs/ocfs2/namei.c:852
>
> Add validation in ocfs2_reserve_suballoc_bits() to check that the
> allocator inode type matches the expected type:
> - Global bitmap allocator must be the cluster bitmap
> - Other allocators (inode, extent) must NOT be the cluster bitmap
>
> This follows the existing pattern of validating OCFS2_CHAIN_FL in the
> same function and uses ocfs2_error() for graceful error handling.
>
> Reported-by: syzbot+44c564a3cb08605f34a1@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=44c564a3cb08605f34a1
> Tested-by: syzbot+44c564a3cb08605f34a1@syzkaller.appspotmail.com
> Link: https://lore.kernel.org/all/20260104014028.305029-1-kartikey406@gmail.com/T/ [v1]
> Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
> ---
> v2: Fix commit message - ocfs2_is_cluster_bitmap() checks ip_blkno
> against bitmap_blkno, not a flag (Joseph Qi)
> ---
> fs/ocfs2/suballoc.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
> index 8e6e5235b30c..fb72c062a8d5 100644
> --- a/fs/ocfs2/suballoc.c
> +++ b/fs/ocfs2/suballoc.c
> @@ -813,6 +813,26 @@ static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
> goto bail;
> }
>
> + /*
> + * Validate allocator type matches expected bitmap type.
> + * Global bitmap must have BITMAP flag, other allocators must not.
> + * This prevents a corrupted filesystem from triggering BUG_ON
> + * in ocfs2_block_group_search() or ocfs2_cluster_group_search().
> + */
> + if (type == GLOBAL_BITMAP_SYSTEM_INODE) {
> + if (!ocfs2_is_cluster_bitmap(alloc_inode)) {
> + status = ocfs2_error(alloc_inode->i_sb,
> + "Global bitmap %llu missing bitmap flag\n",
> + (unsigned long long)le64_to_cpu(fe->i_blkno));
> + goto bail;
> + }
> + } else if (ocfs2_is_cluster_bitmap(alloc_inode)) {
> + status = ocfs2_error(alloc_inode->i_sb,
> + "Allocator %llu has invalid bitmap flag\n",
> + (unsigned long long)le64_to_cpu(fe->i_blkno));
> + goto bail;
> + }
> +
> free_bits = le32_to_cpu(fe->id1.bitmap1.i_total) -
> le32_to_cpu(fe->id1.bitmap1.i_used);
>
> --
> 2.43.0
>
Hi Joseph,
Just wanted to follow up on this patch. Do you have any further
comments or suggestions?
Thanks,
Deepanshu
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v2] ocfs2: validate allocator type to prevent BUG_ON in ocfs2_block_group_search
2026-01-23 6:23 ` Deepanshu Kartikey
@ 2026-01-23 8:38 ` Joseph Qi
0 siblings, 0 replies; 3+ messages in thread
From: Joseph Qi @ 2026-01-23 8:38 UTC (permalink / raw)
To: Deepanshu Kartikey
Cc: ocfs2-devel, linux-kernel, syzbot+44c564a3cb08605f34a1,
Mark Fasheh, Joel Becker, Heming Zhao
On 1/23/26 2:23 PM, Deepanshu Kartikey wrote:
> On Sat, Jan 10, 2026 at 11:14 AM Deepanshu Kartikey
> <kartikey406@gmail.com> wrote:
>>
>> ocfs2_is_cluster_bitmap() checks whether an inode is the global bitmap
>> by comparing ip_blkno with osb->bitmap_blkno. A corrupted filesystem
>> can have either the superblock's bitmap_blkno field corrupted to point
>> to the inode allocator block, or the inode allocator's i_blkno field
>> corrupted to match bitmap_blkno. In either case, ocfs2_is_cluster_bitmap()
>> returns true for the inode allocator.
>>
>> When the code later calls ocfs2_block_group_search(), it triggers
>> BUG_ON(ocfs2_is_cluster_bitmap(inode)) causing a kernel panic.
>>
>> Call trace:
>> ocfs2_block_group_search+0x1c7/0x2c0 fs/ocfs2/suballoc.c:1611
>> ocfs2_search_chain+0x38a/0x1010 fs/ocfs2/suballoc.c:1764
>> ocfs2_claim_suballoc_bits+0x3a4/0x650 fs/ocfs2/suballoc.c:1978
>> ocfs2_claim_new_inode+0x95/0x130 fs/ocfs2/suballoc.c:2137
>> ocfs2_mknod_locked+0x129/0x510 fs/ocfs2/namei.c:568
>> ocfs2_mknod+0x5c7/0x11d0 fs/ocfs2/namei.c:802
>> ocfs2_create+0x136/0x170 fs/ocfs2/namei.c:852
>>
>> Add validation in ocfs2_reserve_suballoc_bits() to check that the
>> allocator inode type matches the expected type:
>> - Global bitmap allocator must be the cluster bitmap
>> - Other allocators (inode, extent) must NOT be the cluster bitmap
>>
>> This follows the existing pattern of validating OCFS2_CHAIN_FL in the
>> same function and uses ocfs2_error() for graceful error handling.
>>
>> Reported-by: syzbot+44c564a3cb08605f34a1@syzkaller.appspotmail.com
>> Closes: https://syzkaller.appspot.com/bug?extid=44c564a3cb08605f34a1
>> Tested-by: syzbot+44c564a3cb08605f34a1@syzkaller.appspotmail.com
>> Link: https://lore.kernel.org/all/20260104014028.305029-1-kartikey406@gmail.com/T/ [v1]
>> Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
>> ---
>> v2: Fix commit message - ocfs2_is_cluster_bitmap() checks ip_blkno
>> against bitmap_blkno, not a flag (Joseph Qi)
>> ---
>> fs/ocfs2/suballoc.c | 20 ++++++++++++++++++++
>> 1 file changed, 20 insertions(+)
>>
>> diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
>> index 8e6e5235b30c..fb72c062a8d5 100644
>> --- a/fs/ocfs2/suballoc.c
>> +++ b/fs/ocfs2/suballoc.c
>> @@ -813,6 +813,26 @@ static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
>> goto bail;
>> }
>>
>> + /*
>> + * Validate allocator type matches expected bitmap type.
>> + * Global bitmap must have BITMAP flag, other allocators must not.
>> + * This prevents a corrupted filesystem from triggering BUG_ON
>> + * in ocfs2_block_group_search() or ocfs2_cluster_group_search().
>> + */
>> + if (type == GLOBAL_BITMAP_SYSTEM_INODE) {
>> + if (!ocfs2_is_cluster_bitmap(alloc_inode)) {
>> + status = ocfs2_error(alloc_inode->i_sb,
>> + "Global bitmap %llu missing bitmap flag\n",
>> + (unsigned long long)le64_to_cpu(fe->i_blkno));
>> + goto bail;
>> + }
>> + } else if (ocfs2_is_cluster_bitmap(alloc_inode)) {
>> + status = ocfs2_error(alloc_inode->i_sb,
>> + "Allocator %llu has invalid bitmap flag\n",
>> + (unsigned long long)le64_to_cpu(fe->i_blkno));
>> + goto bail;
>> + }
>> +
>> free_bits = le32_to_cpu(fe->id1.bitmap1.i_total) -
>> le32_to_cpu(fe->id1.bitmap1.i_used);
>>
>> --
>> 2.43.0
>>
>
>
> Hi Joseph,
>
> Just wanted to follow up on this patch. Do you have any further
> comments or suggestions?
>
Hi，since the inode block is read from disk, it seems we'd better
validate it in ocfs2_validate_inode_block().
Thanks,
Joseph
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-01-10 5:44 [PATCH v2] ocfs2: validate allocator type to prevent BUG_ON in ocfs2_block_group_search Deepanshu Kartikey
2026-01-23 6:23 ` Deepanshu Kartikey
2026-01-23 8:38 ` Joseph Qi
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