Re: [PATCH v3] gdb: z80: Fix endless loop in frame unwinder and validate saved register types

[Kevin Buettner <kevinb@redhat.com>]

Hi Ronald,

This looks great!  Thanks for making the changes I requested.

On Mon, 15 Jun 2026 09:04:01 +0200
Ronald Hecht <ronald.hecht@gmx.de> wrote:

> In z80_frame_unwind_cache, the loop scanning for the frame base pointer
> (for (;; ++sp)) could run into an endless loop or scan too far if the
> termination condition (sp < this_base) was not met due to corrupted
> or unexpected stack layouts. This patch introduces a loop_count to
> limit the scan to a maximum of 2 * addr_len iterations.
> 
> Additionally, when iterating through saved registers to adjust their
> offsets into concrete addresses, the code now explicitly checks if
> the register actually holds an address using is_addr() before calling
> addr(). This prevents potential assertions or undefined behavior for
> registers that do not contain valid address data.
> 
> gdb/ChangeLog:
> 
> 	* z80-tdep.c (z80_frame_unwind_cache): Limit stack scanning
> 	to 2 * addr_len iterations to prevent endless loops. Check
> 	is_addr() before adjusting saved register addresses.

The ChangeLog entry isn't required, but there's no harm in having it in
the commit log.  Regardless, don't add it to any ChangeLog files prior
to pushing it.

Approved-By: Kevin Buettner <kevinb@redhat.com>