Re: [commited] Detect bad debug info

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> Date: Fri, 19 Sep 2008 19:16:12 +0100
> From: Andrew Stubbs <ams@codesourcery.com>
> 
> Hi,
> 
> I have just committed the attached patch (approved privately by Daniel 
> Jacobowitz).
> 
> The patch causes GDB to fail gracefully when it encounters a particular 
> flavour of bad debug info.

Would it be possible to add some detail about this?  "a particular
falvour of bad debug info" is pretty non-informative.

Thanks,

Mark

> 2008-09-19  Andrew Stubbs  <ams@codesourcery.com>
> 
> 	* frame.c (get_frame_register_bytes): Detect bad debug info.
> 
> Index: gdb/frame.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/frame.c,v
> retrieving revision 1.251
> diff -u -p -r1.251 frame.c
> --- gdb/frame.c	26 Aug 2008 17:40:24 -0000	1.251
> +++ gdb/frame.c	19 Sep 2008 18:10:34 -0000
> @@ -796,6 +796,8 @@ get_frame_register_bytes (struct frame_i
>  			  CORE_ADDR offset, int len, gdb_byte *myaddr)
>  {
>    struct gdbarch *gdbarch = get_frame_arch (frame);
> +  int i;
> +  int maxsize;
>  
>    /* Skip registers wholly inside of OFFSET.  */
>    while (offset >= register_size (gdbarch, regnum))
> @@ -804,6 +806,22 @@ get_frame_register_bytes (struct frame_i
>        regnum++;
>      }
>  
> +  /* Detect bad debug info.  */
> +  maxsize = -offset;
> +  for (i = regnum; i < gdbarch_num_regs (gdbarch); i++)
> +    {
> +      int thissize = register_size (gdbarch, i);
> +      if (thissize == 0)
> +	break;
> +      maxsize += thissize;
> +    }
> +  if (len > maxsize)
> +    {
> +      warning (_("Bad debug information detected: "
> +		 "Attempt to read %d bytes from registers."), len);
> +      return 0;
> +    }
> +
>    /* Copy the data.  */
>    while (len > 0)
>      {
> 
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