In the Linux kernel, the following vulnerability has been resolved:
ocfs2: fix readdir position truncation on 32-bit kernels
In ocfs2_dir_foreach_blk_el(), the directory cookie position is
rebuilt with
ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) | offset;
`ctx->pos` is loff_t (signed 64-bit), while `sb->s_blocksize` is
unsigned long. On 32-bit kernels unsigned long is 32-bit, so the mask
~(sb->s_blocksize - 1)
is computed as a 32-bit unsigned value (e.g. 0xfffff000 for a 4 KiB
block size). In the AND expression with the 64-bit `ctx->pos`, that
unsigned operand is zero-extended to 64 bits per the usual arithmetic
conversions, yielding 0x00000000fffff000. The high 32 bits of
`ctx->pos` are silently cleared, even though directory size is
allowed to exceed 4 GiB.
When readdir() crosses the 4 GiB boundary on a 32-bit kernel the
position is reset back into the first 4 GiB block, making the
re-validation path re-enumerate already-returned dirents indefinitely.
This is ocfs2_dir_foreach_blk_el(), the extent-list readdir path taken
for all non-inline directories, so a directory large enough to cross
4 GiB reaches it.
This is the same class of bug that commit 3dce5bb82c97 ("exfat: Fix
bitwise operation having different size") fixed in exfat, and the
fix mirrors the equivalent ext4 fix in this series. Cast the operand
to loff_t so the mask is 64-bit before the AND:
ctx->pos = (ctx->pos & ~((loff_t)sb->s_blocksize - 1)) | offset;
64-bit kernels are unaffected.
ocfs2: fix readdir position truncation on 32-bit kernels
In ocfs2_dir_foreach_blk_el(), the directory cookie position is
rebuilt with
ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) | offset;
`ctx->pos` is loff_t (signed 64-bit), while `sb->s_blocksize` is
unsigned long. On 32-bit kernels unsigned long is 32-bit, so the mask
~(sb->s_blocksize - 1)
is computed as a 32-bit unsigned value (e.g. 0xfffff000 for a 4 KiB
block size). In the AND expression with the 64-bit `ctx->pos`, that
unsigned operand is zero-extended to 64 bits per the usual arithmetic
conversions, yielding 0x00000000fffff000. The high 32 bits of
`ctx->pos` are silently cleared, even though directory size is
allowed to exceed 4 GiB.
When readdir() crosses the 4 GiB boundary on a 32-bit kernel the
position is reset back into the first 4 GiB block, making the
re-validation path re-enumerate already-returned dirents indefinitely.
This is ocfs2_dir_foreach_blk_el(), the extent-list readdir path taken
for all non-inline directories, so a directory large enough to cross
4 GiB reaches it.
This is the same class of bug that commit 3dce5bb82c97 ("exfat: Fix
bitwise operation having different size") fixed in exfat, and the
fix mirrors the equivalent ext4 fix in this series. Cast the operand
to loff_t so the mask is 64-bit before the AND:
ctx->pos = (ctx->pos & ~((loff_t)sb->s_blocksize - 1)) | offset;
64-bit kernels are unaffected.
Metrics
Affected Vendors & Products
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Fixes
Solution
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Workaround
No workaround given by the vendor.
References
History
Sat, 12 Sep 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-190 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 11 Sep 2026 23:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix readdir position truncation on 32-bit kernels In ocfs2_dir_foreach_blk_el(), the directory cookie position is rebuilt with ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1)) | offset; `ctx->pos` is loff_t (signed 64-bit), while `sb->s_blocksize` is unsigned long. On 32-bit kernels unsigned long is 32-bit, so the mask ~(sb->s_blocksize - 1) is computed as a 32-bit unsigned value (e.g. 0xfffff000 for a 4 KiB block size). In the AND expression with the 64-bit `ctx->pos`, that unsigned operand is zero-extended to 64 bits per the usual arithmetic conversions, yielding 0x00000000fffff000. The high 32 bits of `ctx->pos` are silently cleared, even though directory size is allowed to exceed 4 GiB. When readdir() crosses the 4 GiB boundary on a 32-bit kernel the position is reset back into the first 4 GiB block, making the re-validation path re-enumerate already-returned dirents indefinitely. This is ocfs2_dir_foreach_blk_el(), the extent-list readdir path taken for all non-inline directories, so a directory large enough to cross 4 GiB reaches it. This is the same class of bug that commit 3dce5bb82c97 ("exfat: Fix bitwise operation having different size") fixed in exfat, and the fix mirrors the equivalent ext4 fix in this series. Cast the operand to loff_t so the mask is 64-bit before the AND: ctx->pos = (ctx->pos & ~((loff_t)sb->s_blocksize - 1)) | offset; 64-bit kernels are unaffected. | |
| Title | ocfs2: fix readdir position truncation on 32-bit kernels | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-11T19:43:42.808Z
Reserved: 2026-09-11T19:38:34.713Z
Link: CVE-2026-89490
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-11T20:19:30.810
Modified: 2026-09-11T20:19:30.810
Link: CVE-2026-89490
Redhat
OpenCVE Enrichment
Updated: 2026-09-13T00:15:03Z
Weaknesses