CVE-2026-74315
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
In the Linux kernel, the lockd service's nlm4svc_lookup_file() function uses uninitialized bytes in file_hash() when the file handle length is less than LOCKD_FH_HASH_SIZE. This causes the same handle to hash to different buckets, leading to lookup failures. The fix zeroes only the tail bytes that file_hash() would otherwise consume.
Risk Assessment
This can lead to malfunction of the NLM service, potentially causing errors in file locking or crashes. This may affect data integrity.
Recommendation
It is recommended to update the Linux kernel to a version containing the fix that zeroes unused bytes in nlm4svc_lookup_file().
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: lockd: Avoid hashing uninitialized bytes in nlm4svc_lookup_file() file_hash() digests the first LOCKD_FH_HASH_SIZE bytes of nfs_fh.data when bucketing nlm_files[], independent of fh.size. Commit 3de744ee4e45 ("lockd: Use xdrgen XDR functions for the NLMv4 TEST procedure") set .pc_argzero to zero for the converted procedures and moved file-handle population into nlm4svc_lookup_file(), which copies only xdr_lock->fh.len bytes into lock->fh.data. When an NLMv4 client presents a file handle shorter than LOCKD_FH_HASH_SIZE, bytes fh.len..31 retain whatever the argument buffer held from an earlier request. The same wire handle then hashes to different buckets across calls; nlm_lookup_file() misses the existing nlm_file entry, and lock-state lookups fail. Zero only the tail bytes that file_hash() would otherwise consume. Handles of LOCKD_FH_HASH_SIZE or larger already populate every byte that file_hash() reads.