RISC-V: riscv_parse_subset_t's isa_spec is only parser input

[Jan Beulich]

On 08.06.2026 02:37, Alan Modra wrote:
> check_compiler_available fails with a ld segfault linking
> int main (void) { return 0; }
> 
> Program received signal SIGSEGV, Segmentation fault.
> 0x0000000000466a64 in riscv_parse_add_subset (rps=rps@entry=0x7fffffffd450, subset=subset@entry=0x962ca0 "zaamo", major=-1, minor=-1, implicit=implicit@entry=true) at /home/alan/src/binutils-gdb/bfd/elfxx-riscv.c:1947
> 1947	    riscv_get_default_ext_version (*rps->isa_spec, subset,
> (gdb) p rps->isa_spec
> $1 = (const enum riscv_spec_class *) 0x0
> 
> This was triggered when calling riscv_merge_attributes for crti.o
> which had
> (gdb) p ibfd->tdata.elf_obj_data->known_obj_attributes[OBJ_ATTR_PROC][Tag_RISCV_arch]
> $5 = {type = 2, i = 0, s = 0x97e4c0 "rv64i2p1_m2p0_a2p1_f2p2_d2p2_c2p0_zicsr2p0_zifencei2p0_zmmul1p0"}
> 
> Fix the segfault by reinstating a NULL check removed with commit
> 413cf36d8e81

Thanks for fixing this. What I'm puzzled by is that my testsuite runs didn't
hit this case.

Jan

> --- a/bfd/elfxx-riscv.c
> +++ b/bfd/elfxx-riscv.c
> @@ -1942,8 +1942,9 @@ riscv_parse_add_subset (riscv_parse_subset_t *rps,
>    int major_version = major;
>    int minor_version = minor;
>  
> -  if (major_version == RISCV_UNKNOWN_VERSION
> +  if ((major_version == RISCV_UNKNOWN_VERSION
>         || minor_version == RISCV_UNKNOWN_VERSION)
> +      && rps->isa_spec != NULL)
>      riscv_get_default_ext_version (*rps->isa_spec, subset,
>  				   &major_version, &minor_version);
>  
>