Re: [PATCH kdumpid 0/3] Prevent segfault on missing disassembler

On Wed, 28 Jun 2023 14:03:41 -0700
Stephen Brennan <[email protected]> wrote:

> Hi Petr,
> 
> I didn't know quite where to send patches for kdumpid, so I elected to
> send direct to you, and CC the linux-debuggers list. Hope that's ok!


Yes, absolutely! Thank you for the fixes, they are much appreciated.

I should move this project to a better place. In my defense I should
say that the code predates GitHub, and there weren't many options back
then. ;-)

Petr T

> I encountered a segmentation fault of kdumpid (master branch):
> 
> #0  0x0000000000000000 in ?? ()
> #1  0x0000000000406aa9 in disas_at (dd=0x7fffffffde70, info=0x7fffffffdc80, pc=0) at ppc64.c:112
> #2  0x0000000000406d42 in looks_like_kcode_ppc64 (dd=0x7fffffffde70, addr=0) at ppc64.c:174
> #3  0x0000000000405616 in explore_kernel (dd=0x7fffffffde70, fn=0x405880 <explore_utsname>) at util.c:269
> #4  0x0000000000405d3f in explore_raw_data (dd=0x7fffffffde70) at util.c:465
> #5  0x0000000000404c98 in main (argc=2, argv=0x7fffffffe168) at main.c:248
> 
> The print_insn function pointer was NULL and calling it resulted in the
> segfault. So I've included a patch to check the return value of
> disassembler() and avoid calling print_insn in those cases.
> 
> I also added some fixes to build issues I encountered - hopefully to
> help you avoid autotools for even longer :P
> 
> Thanks,
> Stephen
> 
> Stephen Brennan (3):
>   cdefs.sh: require bash
>   Use -lz unconditionally
>   Gracefully handle missing dissasembler function
> 
>  Makefile | 2 +-
>  cdefs.sh | 2 +-
>  libs.sh  | 3 ---
>  ppc.c    | 2 ++
>  ppc64.c  | 2 ++
>  s390.c   | 2 ++
>  x86.c    | 2 ++
>  7 files changed, 10 insertions(+), 5 deletions(-)
>