RE: [PATCH] RISC-V: Fix the static-PIE non-relocated object check

[Palmer Dabbelt <palmer@rivosinc.com>]

On Thu, 22 Feb 2024 18:16:47 PST (-0800), yanzhang.wang@intel.com wrote:
> Hi Palmer,
>
> Thanks for your patch. I have did the full tests with the same change
> as this patch on my qemu-system. There's no regression introduced.
>
> Also test this change with mold linker. It passed.

Awesome, thanks.  I don't have a good setup for this so I was sort of 
just trying to figure it out from poking aroud the code and whatever 
Andres said.

Are you OK posting a Tested-by?  This will probably get backported, so 
best to get that stuff sorted out.

>
> Thanks,
> Yanzhang
>
>> -----Original Message-----
>> From: Palmer Dabbelt <palmer@rivosinc.com>
>> Sent: Friday, February 23, 2024 7:24 AM
>> To: libc-alpha@sourceware.org
>> Cc: schwab@suse.de; Wang, Yanzhang <yanzhang.wang@intel.com>;
>> adhemerval.zanella@linaro.org; Palmer Dabbelt <palmer@rivosinc.com>
>> Subject: [PATCH] RISC-V: Fix the static-PIE non-relocated object check
>> 
>> The value of l_scope is only valid post relocation, so this original check
>> was triggering undefined behavior.  Instead just directly check to see if
>> the object has been relocated, at which point using l_scope is safe.
>> 
>> Reported-by: Andreas Schwab <schwab@suse.de>
>> Closes: BZ #31317
>> Fixes: e0590f41fe ("RISC-V: Enable static-pie.")
>> Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
>> ---
>>  sysdeps/riscv/dl-machine.h | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h index
>> 0cbb476c05..b2f28697f7 100644
>> --- a/sysdeps/riscv/dl-machine.h
>> +++ b/sysdeps/riscv/dl-machine.h
>> @@ -348,7 +348,7 @@ elf_machine_runtime_setup (struct link_map *l, struct
>> r_scope_elem *scope[],
>>        gotplt[1] = (ElfW(Addr)) l;
>>      }
>> 
>> -  if (l->l_type == lt_executable && l->l_scope != NULL)
>> +  if (l->l_type == lt_executable && l->l_relocated)
>>      {
>>        /* The __global_pointer$ may not be defined by the linker if the
>>  	 $gp register does not be used to access the global variable
>> --
>> 2.43.0