[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/CHANGES b/fs/cifs/CHANGES
index bed6215..41e3b6a 100644
--- a/fs/cifs/CHANGES
+++ b/fs/cifs/CHANGES
@@ -6,7 +6,10 @@
Samba supports newer POSIX CIFS Protocol Extensions). Add "nounix"
mount option to allow disabling the CIFS Unix Extensions for just
that mount. Fix hang on spinlock in find_writable_file (race when
-reopening file after session crash).
+reopening file after session crash). Byte range unlock request to
+windows server could unlock more bytes (on server copy of file)
+than intended if start of unlock request is well before start of
+a previous byte range lock that we issued.
Version 1.49
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