Fix array overflow in backtrace on PowerPC (bug 25423)

  When unwinding through a signal frame the backtrace function on PowerPC
didn't check array bounds when storing the frame address.  Fixes commit
d400dcac5e ("PowerPC: fix backtrace to handle signal trampolines").
---
 debug/tst-backtrace5.c                | 12 ++++++++++++
 sysdeps/powerpc/powerpc32/backtrace.c |  2 ++
 sysdeps/powerpc/powerpc64/backtrace.c |  2 ++
 3 files changed, 16 insertions(+)
  

On 21/01/2020 08:31, Andreas Schwab wrote:
> When unwinding through a signal frame the backtrace function on PowerPC
> didn't check array bounds when storing the frame address.  Fixes commit
> d400dcac5e ("PowerPC: fix backtrace to handle signal trampolines").

LGTM, thanks.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

> ---
>  debug/tst-backtrace5.c                | 12 ++++++++++++
>  sysdeps/powerpc/powerpc32/backtrace.c |  2 ++
>  sysdeps/powerpc/powerpc64/backtrace.c |  2 ++
>  3 files changed, 16 insertions(+)
> 
> diff --git a/debug/tst-backtrace5.c b/debug/tst-backtrace5.c
> index e7ce410845..b2f46160e7 100644
> --- a/debug/tst-backtrace5.c
> +++ b/debug/tst-backtrace5.c
> @@ -89,6 +89,18 @@ handle_signal (int signum)
>        }
>    /* Symbol names are not available for static functions, so we do not
>       check do_test.  */
> +
> +  /* Check that backtrace does not return more than what fits in the array
> +     (bug 25423).  */
> +  for (int j = 0; j < NUM_FUNCTIONS; j++)
> +    {
> +      n = backtrace (addresses, j);
> +      if (n > j)
> +	{
> +	  FAIL ();
> +	  return;
> +	}
> +    }
>  }
>  
>  NO_INLINE int
> diff --git a/sysdeps/powerpc/powerpc32/backtrace.c b/sysdeps/powerpc/powerpc32/backtrace.c
> index 7c2d4726f8..d1456c8ae4 100644
> --- a/sysdeps/powerpc/powerpc32/backtrace.c
> +++ b/sysdeps/powerpc/powerpc32/backtrace.c
> @@ -114,6 +114,8 @@ __backtrace (void **array, int size)
>          }
>        if (gregset)
>  	{
> +	  if (count + 1 == size)
> +	    break;
>  	  array[++count] = (void*)((*gregset)[PT_NIP]);
>  	  current = (void*)((*gregset)[PT_R1]);
>  	}
> diff --git a/sysdeps/powerpc/powerpc64/backtrace.c b/sysdeps/powerpc/powerpc64/backtrace.c
> index 65c260ab76..8a53a1088f 100644
> --- a/sysdeps/powerpc/powerpc64/backtrace.c
> +++ b/sysdeps/powerpc/powerpc64/backtrace.c
> @@ -87,6 +87,8 @@ __backtrace (void **array, int size)
>        if (is_sigtramp_address (current->return_address))
>          {
>  	  struct signal_frame_64 *sigframe = (struct signal_frame_64*) current;
> +	  if (count + 1 == size)
> +	    break;
>            array[++count] = (void*) sigframe->uc.uc_mcontext.gp_regs[PT_NIP];
>  	  current = (void*) sigframe->uc.uc_mcontext.gp_regs[PT_R1];
>  	}
>
  

On 21/01/20 6:10 pm, Adhemerval Zanella wrote:
> 
> 
> On 21/01/2020 08:31, Andreas Schwab wrote:
>> When unwinding through a signal frame the backtrace function on PowerPC
>> didn't check array bounds when storing the frame address.  Fixes commit
>> d400dcac5e ("PowerPC: fix backtrace to handle signal trampolines").
> 
> LGTM, thanks.
> 
> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> 
>> ---

OK for master too.

Siddhesh