Re: [dpdk-dev] [PATCH v3] x86/eal: gcc 10 ignore stringop-overflow warnings

[David Marchand <david.marchand@redhat.com>]

On Fri, Apr 17, 2020 at 5:44 PM Kevin Traynor <ktraynor@redhat.com> wrote:
>
> stringop-overflow warns when it sees a possible overflow
> in a string operation.
>
> In the rte_memcpy functions different branches are taken
> depending on the size. stringop-overflow is raised for the
> branches in the function where it sees the static size of the
> src could be overflowed.
>
> However, in reality a correct size argument and in some cases
> dynamic allocation would ensure that this does not happen.
>
> For example, in the case below for key, the correct path will be
> chosen in rte_memcpy_generic at runtime based on the size argument
> but as some paths in the function could lead to a cast to 32 bytes
> a warning is raised.
>
> In function ‘_mm256_storeu_si256’,
> inlined from ‘rte_memcpy_generic’
> at ../lib/librte_eal/common/include/arch/x86/rte_memcpy.h:315:2,
> inlined from ‘iavf_configure_rss_key’
> at ../lib/librte_eal/common/include/arch/x86/rte_memcpy.h:869:10:
>
> /usr/lib/gcc/x86_64-redhat-linux/10/include/avxintrin.h:928:8:
> warning: writing 32 bytes into a region of size 1 [-Wstringop-overflow=]
>   928 |   *__P = __A;
>       |   ~~~~~^~~~~
> In file included
> from ../drivers/net/iavf/../../common/iavf/iavf_prototype.h:10,
> from ../drivers/net/iavf/iavf.h:9,
> from ../drivers/net/iavf/iavf_vchnl.c:22:
>
> ../drivers/net/iavf/iavf_vchnl.c:
> In function ‘iavf_configure_rss_key’:
>
> ../drivers/net/iavf/../../common/iavf/virtchnl.h:508:5:
> note: at offset 0 to object ‘key’ with size 1 declared here
>   508 |  u8 key[1];         /* RSS hash key, packed bytes */
>       |     ^~~
>
> Ignore the stringop-overflow warnings for rte_memcpy.h functions.
>
> Bugzilla ID: 394
> Bugzilla ID: 421
>

Cc: stable@dpdk.org

> Signed-off-by: Kevin Traynor <ktraynor@redhat.com>

Acked-by: Bruce Richardson <bruce.richardson@@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>


Applied, thanks.

-- 
David Marchand