security: commoncap: fix -Wstringop-overread warning
gcc-11 introdces a harmless warning for cap_inode_getsecurity:
security/commoncap.c: In function ‘cap_inode_getsecurity’:
security/commoncap.c:440:33: error: ‘memcpy’ reading 16 bytes from a region of size 0 [-Werror=stringop-overread]
440 | memcpy(&nscap->data, &cap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The problem here is that tmpbuf is initialized to NULL, so gcc assumes
it is not accessible unless it gets set by vfs_getxattr_alloc(). This is
a legitimate warning as far as I can tell, but the code is correct since
it correctly handles the error when that function fails.
Add a separate NULL check to tell gcc about it as well.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
diff --git a/security/commoncap.c b/security/commoncap.c
index 26c1cb7..2bdeacd 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -391,7 +391,7 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
&tmpbuf, size, GFP_NOFS);
dput(dentry);
- if (ret < 0)
+ if (ret < 0 || !tmpbuf)
return ret;
fs_ns = inode->i_sb->s_user_ns;