Re: [PATCH] crypto: Always initialize splitkeylen

[Daniel P . Berrangé]

On Mon, May 22, 2023 at 08:47:37PM +0900, Akihiko Odaki wrote:
> When _FORTIFY_SOURCE=2, glibc version is 2.35, and GCC version is
> 12.1.0, the compiler complains as follows:
> 
> In file included from /usr/include/string.h:535,
>                  from /home/alarm/q/var/qemu/include/qemu/osdep.h:99,
>                  from ../crypto/block-luks.c:21:
> In function 'memset',
>     inlined from 'qcrypto_block_luks_store_key' at 
> ../crypto/block-luks.c:843:9:
> /usr/include/bits/string_fortified.h:59:10: error: 'splitkeylen' may be used 
> uninitialized [-Werror=maybe-uninitialized]
>    59 |   return __builtin___memset_chk (__dest, __ch, __len,
>       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>    60 |                                  __glibc_objsize0 (__dest));
>       |                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../crypto/block-luks.c: In function 'qcrypto_block_luks_store_key':
> ../crypto/block-luks.c:699:12: note: 'splitkeylen' was declared here
>   699 |     size_t splitkeylen;
>       |            ^~~~~~~~~~~
> 
> It seems the compiler cannot see that splitkeylen will not be used
> when splitkey is NULL. Suppress the warning by initializing splitkeylen
> even when splitkey stays NULL.
> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>  crypto/block-luks.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

and queued.


With regards,
Daniel
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