# Re: \[PATCH 03/11\] security: commoncap: fix -Wstringop-overread warning

- From: James Morris \<jmorris@namei.org\>
- Date: 2021-03-24 20:56:06 
- List: linux-wireless
- Page: https://ratatoskr.run/linux-wireless/2021/03/6314308
- Thread: https://ratatoskr.run/linux-arm-kernel/2021/03/6310878/t.md

```text
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

-- 
James Morris
[ref]
```