Re: [PATCH] gdb: fix assert after register write failure

[Guinevere Larsen <guinevere@redhat.com>]

On 10/12/26 7:38 AM, Stephan Rohr wrote:
> From: Eduard Sargsyan <eduard.sargsyan@intel.com>
>
> GDB tries to invalidate register cache if write to register fails.  In case
> when write was requested to be done for a remote inferior and connection with
> remote is dead (so write request will fail) GDB cleans register caches and as
> result setting register status fails with segmentation fault, because internal
> pointers are not valid anymore and the unique_ptr with register status is
> null.
>
> This change adds check if register status cache is still valid before trying to
> modify (set status to UNKNOWN).
> ---

Hi! Thanks for working on this!

I wonder if it would be better to move this check to 
regcache::invalidate instead, so that we don't need to make this check 
every time invalidate is called in this kind of situation.

-- 
Cheers,
Guinevere Larsen
it/its
she/her (deprecated)

>   gdb/regcache.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/gdb/regcache.c b/gdb/regcache.c
> index 773e8ac37d0..01c60ea8047 100644
> --- a/gdb/regcache.c
> +++ b/gdb/regcache.c
> @@ -883,8 +883,11 @@ regcache::raw_write (int regnum, gdb::array_view<const gdb_byte> src)
>   
>     /* Invalidate the register after it is written, in case of a
>        failure.  */
> -  auto invalidator
> -    = make_scope_exit ([&] { this->invalidate (regnum); });
> +  auto invalidator = make_scope_exit ([&]
> +    {
> +      if (this->m_register_status != nullptr)
> +	this->invalidate (regnum);
> +    });
>   
>     target_store_registers (this, regnum);
>