cifs: Replace wrtPending with a real reference count
Currently, cifs_close() tries to wait until all I/O is complete and then
frees the file private data. If I/O does not completely in a reasonable
amount of time it frees the structure anyway, leaving a potential use-
after-free situation.
This patch changes the wrtPending counter to a complete reference count and
lets the last user free the structure.
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Tested-by: Shirish Pargaonkar <shirishp@us.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index f100399..6cfc81a 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -351,11 +351,24 @@
bool closePend:1; /* file is marked to close */
bool invalidHandle:1; /* file closed via session abend */
bool messageMode:1; /* for pipes: message vs byte mode */
- atomic_t wrtPending; /* handle in use - defer close */
+ atomic_t count; /* reference count */
struct mutex fh_mutex; /* prevents reopen race after dead ses*/
struct cifs_search_info srch_inf;
};
+/* Take a reference on the file private data */
+static inline void cifsFileInfo_get(struct cifsFileInfo *cifs_file)
+{
+ atomic_inc(&cifs_file->count);
+}
+
+/* Release a reference on the file private data */
+static inline void cifsFileInfo_put(struct cifsFileInfo *cifs_file)
+{
+ if (atomic_dec_and_test(&cifs_file->count))
+ kfree(cifs_file);
+}
+
/*
* One of these for each file inode
*/
