From: Paulo Alcantara <pc@cjr.nz>
Date: Fri, 2 Jul 2021 14:50:54 +0000 (-0300)
Subject: cifs: prevent NULL deref in cifs_compose_mount_options()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=03313d1c3a2f086bb60920607ab79ac8f8578306;p=linux.git

cifs: prevent NULL deref in cifs_compose_mount_options()

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>
---

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index ec57cdb1590f7..57f91311fdaa3 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 */