Re: [PATCH] selftests: mptcp: initialize raw_addr to Null

[Matthieu Baerts]

Hi Ankit,

On 26/11/2025 17:30, Ankit Khushwaha wrote:
> The "void *raw_addr" is left uninitialized when else path is
> followed raising below warning.
> 
> mptcp_connect.c:1262:11: warning: variable 'raw_addr' is used
>       uninitialized whenever 'if' condition is false
>       [-Wsometimes-uninitialized]
> 
> so the fix is to assign *raw_addr to NULL to suppress the warning.

Thank you for having shared this patch!
> Signed-off-by: Ankit Khushwaha <ankitkhushwaha.linux@xxxxxxxxx>
> ---
> compiler used: clang version 21.1.5 (Fedora 21.1.5-1.fc43).
> compilation cmd used:
> 	make -C tools/testing/selftests/net/mptcp CC=clang V=1 -j8
> 
> this maybe also be false positive. But somehow clang - 21.1.5
> triggering this.

I confirm this, I can reproduce the warning with Clang 21.

It is indeed a false positive, because the code does that:


  if (addr.ss_family == AF_INET)
          raw_addr = &(((struct sockaddr_in *)&addr)->sin_addr);
  else if (addr.ss_family == AF_INET6)
          raw_addr = &(((struct sockaddr_in6 *)&addr)->sin6_addr);
  else
          xerror("bad family");


"xerror()" calls "exit(1)", so "raw_addr" is never used uninitialized.

I'm not sure why Clang 21 reports that now, and not before, but well,
the modification you did in the selftests doesn't hurt:

Reviewed-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx>


@Net maintainers: this patch can be applied in 'net' directly.


@Antik: next time, please specify the target (net/net-next) in the
subject, see [1]. No need to send a new version (except if the Net
maintainers prefer), this patch can be applied on top of "net" without
conflicts.

[1] https://docs.kernel.org/process/maintainer-netdev.html

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.