Re: [PATCH 1/2] gdb: fix possible nullptr dereference in a remote_debug_printf call

Andrew Burgess via Gdb-patches
2023-08-03T09:07:50Z

Tom Tromey <tom@tromey.com> writes:

>>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:
>
> Andrew> While working on the next patch I triggered a segfault from within the
> Andrew> function remote_target::discard_pending_stop_replies. Turns out this
> Andrew> was caused by a cut&paste error introduced in this commit:
>
> Andrew> commit df5ad102009c41ab4dfadbb8cfb8c8b2a02a4f78
> Andrew> Date: Wed Dec 1 09:40:03 2021 -0500
>
> Andrew> gdb, gdbserver: detach fork child when detaching from fork parent
>
> Andrew> This commit adds a remote_debug_printf call that was copied from
> Andrew> earlier in the function, however, the new call wasn't updated to use
> Andrew> the appropriate local variable. The local variable that it is using
> Andrew> might be nullptr, in which case we trigger undefined behaviour, and
> Andrew> could crash, which is what I was seeing.
>
> Andrew> Fixed by updating to use the correct local variable.
>
> Seems obvious to me FWIW.

I updated the commit message to not mention "the next patch", and pushed
this fix.

Thanks,
Andrew