CVE-2026-89490
Low risk· EPSS 7%Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
In the Linux kernel, the ocfs2 function ocfs2_dir_foreach_blk_el() on 32-bit kernels incorrectly computed the directory position mask, clearing the high 32 bits of the position. When readdir() crossed the 4 GiB boundary, the position was reset, causing infinite re-enumeration of already-returned directory entries.
Risk Assessment
On 32-bit systems with OCFS2 directories larger than 4 GiB, readdir() may loop indefinitely, causing a process or system hang (denial of service).
Recommendation
Update the Linux kernel to a version containing the fix that casts sb->s_blocksize to loff_t before the AND operation. 64-bit kernels are unaffected.
Other vulnerabilities in Linux kernel (ocfs2)
See all- CVE-2026-89494Critical
In the Linux kernel, the ocfs2 dlm_mig_lockres_handler trusted the num_locks and lockname_len fields from a DLM_MIG_LOCKRES message without validation. This led to an out-of-bounds read (BUG_ON panic) and a heap out-of-bounds write when copying the lock name into a fixed 32-byte object. Any node in the domain could trigger this.
- CVE-2026-89492Critical
A vulnerability was found in the Linux kernel's ocfs2 module due to missing validation of directory-index entry counts when reading metadata. The functions ocfs2_validate_dx_leaf() and ocfs2_validate_dx_root() do not bound the de_num_used and de_count fields against the block capacity, allowing a crafted on-disk image to set them to 0xffff and cause an out-of-bounds read past the 4KB metadata block. The flaw is reachable from any path lookup, stat() or open() on an indexed directory once the image is mounted.
- CVE-2026-90301High
In the Linux kernel, the ocfs2 (o2hb) subsystem has a use-after-free bug in the heartbeat region lifecycle. The region is published to the o2net handler table before its delayed works are initialized, and teardown does not fully drain in-flight o2net callbacks. This causes a race and use of freed memory (KASAN slab-use-after-free in __run_timers).
- CVE-2026-89496Low risk· EPSS 7%
In the Linux kernel, the ocfs2 filesystem has a memory leak during copy-on-write operations triggered by copy_file_range() within the same filesystem. The issue was found by fuzzing and occurs because deallocations are not always run on copy-on-write completion, leading to unreferenced memory allocations.
- CVE-2026-89493High
The Linux kernel ocfs2 module lacked validation of the rl_used and rl_count fields in the refcount block. A crafted or corrupted ocfs2 image with rl_used set to 0xffff causes an out-of-bounds read past the metadata block and a subsequent out-of-bounds memmove during a reflink (FICLONE) operation. Exploitation requires local access (CAP_SYS_ADMIN mounting a crafted image or raw write to the backing block device).
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS