[CIFS] Byte range unlock request to non-Unix server can unlock too much
On a mount without posix extensions enabled, when an unlock request is
made, the client can release more than is intended. To reproduce, on a
CIFS mount without posix extensions enabled:
1) open file
2) do fcntl lock: start=0 len=1
3) do fcntl lock: start=2 len=1
4) do fcntl unlock: start=0 len=1
...on the unlock call the client sends an unlock request to the server
for both locks. The problem is a bad test in cifs_lock.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 894b1f7..f9bd8b8 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -767,7 +767,8 @@
mutex_lock(&fid->lock_mutex);
list_for_each_entry_safe(li, tmp, &fid->llist, llist) {
if (pfLock->fl_start <= li->offset &&
- length >= li->length) {
+ (pflock->fl_start + length) >=
+ (li->offset + li->length)) {
stored_rc = CIFSSMBLock(xid, pTcon,
netfid,
li->length, li->offset,