commoncap: move assignment of fs_ns to avoid null pointer dereference

The pointer fs_ns is assigned from inode->i_ib->s_user_ns before a null pointer check on inode, hence if inode is actually null we will get a null pointer dereference on this assignment. Fix this by only dereferencing inode after the null pointer check on inode. Detected by CoverityScan CID#1455328 ("Dereference before null check") Fixes: 8db6c34 ("Introduce v3 namespaced file capabilities") Signed-off-by: Colin Ian King <[email protected]> Cc: [email protected] Acked-by: Serge Hallyn <[email protected]> Signed-off-by: James Morris <[email protected]>
opendata26 · Oct 19, 2017 · 76ba89c · 76ba89c
1 parent 494b9ae
commit 76ba89c
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/security/commoncap.c b/security/commoncap.c
@@ -585,13 +585,14 @@ int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data
 	struct vfs_ns_cap_data data, *nscaps = &data;
 	struct vfs_cap_data *caps = (struct vfs_cap_data *) &data;
 	kuid_t rootkuid;
-	struct user_namespace *fs_ns = inode->i_sb->s_user_ns;
+	struct user_namespace *fs_ns;
 
 	memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
 
 	if (!inode)
 		return -ENODATA;
 
+	fs_ns = inode->i_sb->s_user_ns;
 	size = __vfs_getxattr((struct dentry *)dentry, inode,
 			      XATTR_NAME_CAPS, &data, XATTR_CAPS_SZ);
 	if (size == -ENODATA || size == -EOPNOTSUPP)