[PATCH] PR32870: ld: arm32: fix segfault when linking with LLVMgold.so plugin under LTO

[Richard Earnshaw]

On 15/04/2025 10:14, dongjianqiang (A) wrote:
> Hi,
> 
> Proposed patch to PR32870.
> When handling the iplt in ARM32, the ld must check whether the input_bfd
> is in ELF format. If the input is an LLVM Bitcode file, an error will be raised.
> 
> Any suggestions? Thanks.
> 
> ---
> 	PR 32870
> 	* elf32-arm.c (elf32_arm_output_arch_local_syms): Check input_bfd
> 
> diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
> index 3b7cee3de1c..3af964ce034 100644
> --- a/bfd/elf32-arm.c
> +++ b/bfd/elf32-arm.c
> @@ -18345,6 +18345,9 @@ elf32_arm_output_arch_local_syms (bfd *output_bfd,
>   	  struct arm_local_iplt_info **local_iplt;
>   	  unsigned int i, num_syms;
>   
> +	  if (!is_arm_elf (input_bfd))
> +	    continue;
> +
>   	  local_iplt = elf32_arm_local_iplt (input_bfd);
>   	  if (local_iplt != NULL)
>   	    {

I'd like Alan's opinion on this one.  To me it's strange that something 
that is not remotely like a object file is still in the list of input 
BFDs at this point.  This feels like it might be yet another rich source 
of fuzzing bugs.

If keeping this in the bfd list is correct, then I think a better fix 
would be to refuse to create a local iplt for this bfd; then we'll 
simply skip the following code because elf32_arm_local_iplt will simply 
return NULL.

R.