diff options
| author | Chuck Lever <chuck.lever@oracle.com> | 2026-05-14 16:56:07 -0400 |
|---|---|---|
| committer | Chuck Lever <cel@kernel.org> | 2026-06-09 16:32:59 -0400 |
| commit | 6e4c62caecf792e8a15ad9bc7f371e57c17e3302 (patch) | |
| tree | 26672bab523c306e6dd28775ed97caf9c34774ea | |
| parent | 70a38f87bed7f0694fd07988b47b2db1e10d8df3 (diff) | |
| download | lwn-6e4c62caecf792e8a15ad9bc7f371e57c17e3302.tar.gz lwn-6e4c62caecf792e8a15ad9bc7f371e57c17e3302.zip | |
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.
Reported-by: Jeff Layton <jlayton@kernel.org>
Closes: https://lore.kernel.org/r/5229a9746d723a3f830120c0b966510f75badfc2.camel@kernel.org
Fixes: 3de744ee4e45 ("lockd: Use xdrgen XDR functions for the NLMv4 TEST procedure")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
| -rw-r--r-- | fs/lockd/lockd.h | 8 | ||||
| -rw-r--r-- | fs/lockd/svc4proc.c | 3 | ||||
| -rw-r--r-- | fs/lockd/svcsubs.c | 3 |
3 files changed, 12 insertions, 2 deletions
diff --git a/fs/lockd/lockd.h b/fs/lockd/lockd.h index 0be0dac59ea2..e418a50c4180 100644 --- a/fs/lockd/lockd.h +++ b/fs/lockd/lockd.h @@ -52,6 +52,14 @@ */ #define LOCKD_DFLT_TIMEO 10 +/* + * Number of leading bytes of nfs_fh.data that file_hash() + * digests when bucketing nlm_files[]. Sized for historical + * NFSv2 handles; nfs_fh.data must be initialized at least + * this far before lookup, regardless of fh.size. + */ +#define LOCKD_FH_HASH_SIZE 32 + /* error codes new to NLMv4 */ #define nlm4_deadlock cpu_to_be32(NLM_DEADLCK) #define nlm4_rofs cpu_to_be32(NLM_ROFS) diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c index 997f4f437997..78e675470c4b 100644 --- a/fs/lockd/svc4proc.c +++ b/fs/lockd/svc4proc.c @@ -156,6 +156,9 @@ nlm4svc_lookup_file(struct svc_rqst *rqstp, struct nlm_host *host, return nlm_lck_denied_nolocks; lock->fh.size = xdr_lock->fh.len; memcpy(lock->fh.data, xdr_lock->fh.data, xdr_lock->fh.len); + if (xdr_lock->fh.len < LOCKD_FH_HASH_SIZE) + memset(lock->fh.data + xdr_lock->fh.len, 0, + LOCKD_FH_HASH_SIZE - xdr_lock->fh.len); lock->oh.len = xdr_lock->oh.len; lock->oh.data = xdr_lock->oh.data; diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c index 58b87ec52930..a0d1a6fbf61e 100644 --- a/fs/lockd/svcsubs.c +++ b/fs/lockd/svcsubs.c @@ -17,7 +17,6 @@ #include <linux/sunrpc/addr.h> #include <linux/module.h> #include <linux/mount.h> -#include <uapi/linux/nfs2.h> #include "lockd.h" #include "share.h" @@ -67,7 +66,7 @@ static inline unsigned int file_hash(struct nfs_fh *f) { unsigned int tmp=0; int i; - for (i=0; i<NFS2_FHSIZE;i++) + for (i = 0; i < LOCKD_FH_HASH_SIZE; i++) tmp += f->data[i]; return tmp & (FILE_NRHASH - 1); } |