On Mon, 22 Mar 2021, Arnd Bergmann wrote:
From: Arnd Bergmann arnd@arndb.de
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
Applied to git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security.git fixes-v5.12