Re: [PATCH] btf_encoder: Add extra checks for symbol names

[Tom Stellard <tstellar@redhat.com>]

On 1/13/21 11:50 PM, Sedat Dilek wrote:
> On Wed, Jan 13, 2021 at 1:28 AM Tom Stellard <tstellar@redhat.com> wrote:
>>
>> On 1/12/21 10:40 AM, Jiri Olsa wrote:
>>> When processing kernel image build by clang we can
>>> find some functions without the name, which causes
>>> pahole to segfault.
>>>
>>> Adding extra checks to make sure we always have
>>> function's name defined before using it.
>>>
>>
>> I backported this patch to pahole 1.19, and I can confirm it fixes the
>> segfault for me.
>>
> 
> Thanks for testing.
> 
> Can you give me Git commit-id of LLVM-12 you tried?
> 

I was building with LLVM 11.0.1

-Tom

> - Sedat -
> 
>> -Tom
>>
>>> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
>>> ---
>>>    btf_encoder.c | 8 ++++++--
>>>    1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/btf_encoder.c b/btf_encoder.c
>>> index 333973054b61..17f7a14f2ef0 100644
>>> --- a/btf_encoder.c
>>> +++ b/btf_encoder.c
>>> @@ -72,6 +72,8 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym)
>>>
>>>        if (elf_sym__type(sym) != STT_FUNC)
>>>                return 0;
>>> +     if (!elf_sym__name(sym, btfe->symtab))
>>> +             return 0;
>>>
>>>        if (functions_cnt == functions_alloc) {
>>>                functions_alloc = max(1000, functions_alloc * 3 / 2);
>>> @@ -730,9 +732,11 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force,
>>>                if (!has_arg_names(cu, &fn->proto))
>>>                        continue;
>>>                if (functions_cnt) {
>>> -                     struct elf_function *func;
>>> +                     const char *name = function__name(fn, cu);
>>> +                     struct elf_function *func = NULL;
>>>
>>> -                     func = find_function(btfe, function__name(fn, cu));
>>> +                     if (name)
>>> +                             func = find_function(btfe, name);
>>>                        if (!func || func->generated)
>>>                                continue;
>>>                        func->generated = true;
>>>
>>
>