[PATCH AUTOSEL 5.12 102/102] cifs: prevent NULL deref in cifs_compose_mount_options()

Sasha Levin
2021-07-14T19:49:56Z

From: Paulo Alcantara <pc@cjr.nz>

[ Upstream commit 03313d1c3a2f086bb60920607ab79ac8f8578306 ]

The optional @ref parameter might contain an NULL node_name, so
prevent dereferencing it in cifs_compose_mount_options().

Addresses-Coverity: 1476408 ("Explicit null dereferenced")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/cifs_dfs_ref.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index 6b1ce4efb591..2891089aadbb 100644
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -151,6 +151,9 @@ char *cifs_compose_mount_options(const char *sb_mountdata,
return ERR_PTR(-EINVAL);

if (ref) {
+ if (WARN_ON_ONCE(!ref->node_name || ref->path_consumed < 0))
+ return ERR_PTR(-EINVAL);
+
if (strlen(fullpath) - ref->path_consumed) {
prepath = fullpath + ref->path_consumed;
/* skip initial delimiter */
--
2.30.2