[OBV] Fix stack buffer overflow in aarch64_extract_return_value

  Hi,
I build GDB with -fsanitize=address, and run testsuite.  In
gdb.base/callfuncs.exp, I see the following error,

p/c fun1()
  

On 15-11-16 10:33 AM, Yao Qi wrote:
> Hi,
> I build GDB with -fsanitize=address, and run testsuite.  In
> gdb.base/callfuncs.exp, I see the following error,
> 
> p/c fun1()
> =================================================================^M
> ==9601==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fffee858530 at pc 0x6df079 bp 0x7fffee8583a0 sp 0x7fffee858398
> WRITE of size 16 at 0x7fffee858530 thread T0
>     #0 0x6df078 in regcache_raw_read /home/yao/SourceCode/gnu/gdb/git/gdb/regcache.c:673
>     #1 0x6dfe1e in regcache_cooked_read /home/yao/SourceCode/gnu/gdb/git/gdb/regcache.c:751
>     #2 0x4696a3 in aarch64_extract_return_value /home/yao/SourceCode/gnu/gdb/git/gdb/aarch64-tdep.c:1708
>     #3 0x46ae57 in aarch64_return_value /home/yao/SourceCode/gnu/gdb/git/gdb/aarch64-tdep.c:1918
> 
> We are extracting return value from V registers (128 bit), but only
> allocate X_REGISTER_SIZE-byte array, which isn't sufficient.  This
> patch changes the array to V_REGISTER_SIZE.
> 
> It's ovbious.  I'll push it in.
> 
> gdb:
> 
> 2015-11-16  Yao Qi  <yao.qi@linaro.org>
> 
> 	* aarch64-tdep.c (aarch64_extract_return_value):  Change array
> 	buf's length to V_REGISTER_SIZE.
> ---
>  gdb/aarch64-tdep.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/gdb/aarch64-tdep.c b/gdb/aarch64-tdep.c
> index 4b82553..4fa555d 100644
> --- a/gdb/aarch64-tdep.c
> +++ b/gdb/aarch64-tdep.c
> @@ -1630,7 +1630,7 @@ aarch64_extract_return_value (struct type *type, struct regcache *regs,
>        for (i = 0; i < elements; i++)
>  	{
>  	  int regno = AARCH64_V0_REGNUM + i;
> -	  bfd_byte buf[X_REGISTER_SIZE];
> +	  bfd_byte buf[V_REGISTER_SIZE];
>  
>  	  if (aarch64_debug)
>  	    {
> 

Hi Yao,

-fsanitize=address is awesome.  Do you think we could always run tests with it enabled on buildbot?

Simon
  

Simon Marchi <simon.marchi@ericsson.com> writes:

> Hi Yao,
>
> -fsanitize=address is awesome.  Do you think we could always run tests
> with it enabled on buildbot?

Yes, but we need to fix these existing errors found by
-fsanitize=address first.  I built GDB for aarch64-linux with
-fsanitize=address, and run tests.  There are still some errors to be
fixed, while most of them are not arch-specific.