In the Linux kernel, the following vulnerability has been resolved:
ext2/dax: Fix ext2_setsize when len is page aligned
PAGE_ALIGN(x) macro gives the next highest value which is multiple of
pagesize. But if x is already page aligned then it simply returns x.
So, if x passed is 0 in dax_zero_range() function, that means the
length gets passed as 0 to ->iomap_begin().
In ext2 it then calls ext2_get_blocks -> max_blocks as 0 and hits bug_on
here in ext2_get_blocks().
BUG_ON(maxblocks == 0);
Instead we should be calling dax_truncate_page() here which takes
care of it. i.e. it only calls dax_zero_range if the offset is not
page/block aligned.
This can be easily triggered with following on fsdax mounted pmem
device.
dd if=/dev/zero of=file count=1 bs=512
truncate -s 0 file
[79.525838] EXT2-fs (pmem0): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
[79.529376] ext2 filesystem being mounted at /mnt1/test supports timestamps until 2038 (0x7fffffff)
[93.793207] ------------[ cut here ]------------
[93.795102] kernel BUG at fs/ext2/inode.c:637!
[93.796904] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[93.798659] CPU: 0 PID: 1192 Comm: truncate Not tainted 6.3.0-rc2-xfstests-00056-g131086faa369 #139
[93.806459] RIP: 0010:ext2_get_blocks.constprop.0+0x524/0x610
<...>
[93.835298] Call Trace:
[93.836253] <TASK>
[93.837103] ? lock_acquire+0xf8/0x110
[93.838479] ? d_lookup+0x69/0xd0
[93.839779] ext2_iomap_begin+0xa7/0x1c0
[93.841154] iomap_iter+0xc7/0x150
[93.842425] dax_zero_range+0x6e/0xa0
[93.843813] ext2_setsize+0x176/0x1b0
[93.845164] ext2_setattr+0x151/0x200
[93.846467] notify_change+0x341/0x4e0
[93.847805] ? lock_acquire+0xf8/0x110
[93.849143] ? do_truncate+0x74/0xe0
[93.850452] ? do_truncate+0x84/0xe0
[93.851739] do_truncate+0x84/0xe0
[93.852974] do_sys_ftruncate+0x2b4/0x2f0
[93.854404] do_syscall_64+0x3f/0x90
[93.855789] entry_SYSCALL_64_after_hwframe+0x72/0xdc
ext2/dax: Fix ext2_setsize when len is page aligned
PAGE_ALIGN(x) macro gives the next highest value which is multiple of
pagesize. But if x is already page aligned then it simply returns x.
So, if x passed is 0 in dax_zero_range() function, that means the
length gets passed as 0 to ->iomap_begin().
In ext2 it then calls ext2_get_blocks -> max_blocks as 0 and hits bug_on
here in ext2_get_blocks().
BUG_ON(maxblocks == 0);
Instead we should be calling dax_truncate_page() here which takes
care of it. i.e. it only calls dax_zero_range if the offset is not
page/block aligned.
This can be easily triggered with following on fsdax mounted pmem
device.
dd if=/dev/zero of=file count=1 bs=512
truncate -s 0 file
[79.525838] EXT2-fs (pmem0): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
[79.529376] ext2 filesystem being mounted at /mnt1/test supports timestamps until 2038 (0x7fffffff)
[93.793207] ------------[ cut here ]------------
[93.795102] kernel BUG at fs/ext2/inode.c:637!
[93.796904] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[93.798659] CPU: 0 PID: 1192 Comm: truncate Not tainted 6.3.0-rc2-xfstests-00056-g131086faa369 #139
[93.806459] RIP: 0010:ext2_get_blocks.constprop.0+0x524/0x610
<...>
[93.835298] Call Trace:
[93.836253] <TASK>
[93.837103] ? lock_acquire+0xf8/0x110
[93.838479] ? d_lookup+0x69/0xd0
[93.839779] ext2_iomap_begin+0xa7/0x1c0
[93.841154] iomap_iter+0xc7/0x150
[93.842425] dax_zero_range+0x6e/0xa0
[93.843813] ext2_setsize+0x176/0x1b0
[93.845164] ext2_setattr+0x151/0x200
[93.846467] notify_change+0x341/0x4e0
[93.847805] ? lock_acquire+0xf8/0x110
[93.849143] ? do_truncate+0x74/0xe0
[93.850452] ? do_truncate+0x84/0xe0
[93.851739] do_truncate+0x84/0xe0
[93.852974] do_sys_ftruncate+0x2b4/0x2f0
[93.854404] do_syscall_64+0x3f/0x90
[93.855789] entry_SYSCALL_64_after_hwframe+0x72/0xdc
Metrics
Affected Vendors & Products
No data.
No data.
No data.
No data.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Tue, 16 Sep 2025 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ext2/dax: Fix ext2_setsize when len is page aligned PAGE_ALIGN(x) macro gives the next highest value which is multiple of pagesize. But if x is already page aligned then it simply returns x. So, if x passed is 0 in dax_zero_range() function, that means the length gets passed as 0 to ->iomap_begin(). In ext2 it then calls ext2_get_blocks -> max_blocks as 0 and hits bug_on here in ext2_get_blocks(). BUG_ON(maxblocks == 0); Instead we should be calling dax_truncate_page() here which takes care of it. i.e. it only calls dax_zero_range if the offset is not page/block aligned. This can be easily triggered with following on fsdax mounted pmem device. dd if=/dev/zero of=file count=1 bs=512 truncate -s 0 file [79.525838] EXT2-fs (pmem0): DAX enabled. Warning: EXPERIMENTAL, use at your own risk [79.529376] ext2 filesystem being mounted at /mnt1/test supports timestamps until 2038 (0x7fffffff) [93.793207] ------------[ cut here ]------------ [93.795102] kernel BUG at fs/ext2/inode.c:637! [93.796904] invalid opcode: 0000 [#1] PREEMPT SMP PTI [93.798659] CPU: 0 PID: 1192 Comm: truncate Not tainted 6.3.0-rc2-xfstests-00056-g131086faa369 #139 [93.806459] RIP: 0010:ext2_get_blocks.constprop.0+0x524/0x610 <...> [93.835298] Call Trace: [93.836253] <TASK> [93.837103] ? lock_acquire+0xf8/0x110 [93.838479] ? d_lookup+0x69/0xd0 [93.839779] ext2_iomap_begin+0xa7/0x1c0 [93.841154] iomap_iter+0xc7/0x150 [93.842425] dax_zero_range+0x6e/0xa0 [93.843813] ext2_setsize+0x176/0x1b0 [93.845164] ext2_setattr+0x151/0x200 [93.846467] notify_change+0x341/0x4e0 [93.847805] ? lock_acquire+0xf8/0x110 [93.849143] ? do_truncate+0x74/0xe0 [93.850452] ? do_truncate+0x84/0xe0 [93.851739] do_truncate+0x84/0xe0 [93.852974] do_sys_ftruncate+0x2b4/0x2f0 [93.854404] do_syscall_64+0x3f/0x90 [93.855789] entry_SYSCALL_64_after_hwframe+0x72/0xdc | |
| Title | ext2/dax: Fix ext2_setsize when len is page aligned | |
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-09-16T16:11:58.877Z
Reserved: 2025-09-16T16:08:59.563Z
Link: CVE-2023-53323
Vulnrichment
No data.
NVD
Status : Received
Published: 2025-09-16T17:15:38.410
Modified: 2025-09-16T17:15:38.410
Link: CVE-2023-53323
Redhat
No data.
OpenCVE Enrichment
No data.