CVE-2026-89782

Summary

In the Linux kernel, the following vulnerability has been resolved:

fs/ntfs3: reject restart table growth beyond U16_MAX entries

During $LogFile replay, log_replay() indexes the transaction table by the transact_id taken from the log record header. check_log_rec() only verifies that transact_id is non-zero and properly aligned, not its magnitude, so a crafted image can request an arbitrarily large index.

alloc_rsttbl_from_idx() grows the table to cover that index via extend_rsttbl(), which passes the new entry count to init_rsttbl():

rt = init_rsttbl(esize, used + add);

used + add is computed as u32 but init_rsttbl() takes a u16, and the count is stored in struct RESTART_TABLE as a __le16. When used + add exceeds U16_MAX it is truncated, init_rsttbl() allocates a table far smaller than the index requires, and alloc_rsttbl_from_idx() then dereferences and writes at the original, untruncated offset – an out-of-bounds access past the allocation, reachable by mounting a crafted NTFS image.

BUG: KASAN: use-after-free in alloc_rsttbl_from_idx (fs/ntfs3/fslog.c:950) Read of size 4 at addr ffff8880327ffff8 by task exploit alloc_rsttbl_from_idx (fs/ntfs3/fslog.c:950) log_replay (fs/ntfs3/fslog.c:4562) ntfs_loadlog_and_replay (fs/ntfs3/fsntfs.c:324) ntfs_fill_super (fs/ntfs3/super.c:1393) get_tree_bdev_flags vfs_get_tree path_mount __x64_sys_mount

A restart table is limited to U16_MAX entries by its __le16 count, so a larger growth request is invalid input. Reject it in extend_rsttbl(); all callers already handle a NULL return.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/caa0ec3fc44a13d7c21d78e4722f4f05f87ccf56
• https://git.kernel.org/stable/c/339e59996ff193adcf1c438cf05f19e753beb3a7
• https://git.kernel.org/stable/c/ecde45cd81dc28f5696c312c5ce5a509962e9ab1
• https://git.kernel.org/stable/c/be218a01aadffe33ed4fc73e25276d676ebbd09d
• https://git.kernel.org/stable/c/aad605a450611e2a7b7cf9dd5724004d39192bfb
• https://git.kernel.org/stable/c/967a5ff8a614d10126b6d46db1ac040948d6cb42
• https://git.kernel.org/stable/c/111f8d74a19d85942ecbb3aba78f6f3c88e59391

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