Re: [PATCH] malloc: Simplify implementation of __malloc_assert

[Carlos O'Donell <carlos@redhat.com>]

On 7/21/22 07:43, Siddhesh Poyarekar wrote:
> On 2022-07-21 06:34, Florian Weimer via Libc-alpha wrote:
>> It is prudent not to run too much code after detecting heap
>> corruption, and __fxprintf is really complex.  The line number
>> and file name do not carry much information, so it is not included
>> in the error message.  (__libc_message only supports %s formatting.)
>> The function name and assertion should provide some context.
>>
>> Tested on i686-linux-gnu and x86_64-linux-gnu.  Also emulated the
>> __libc_message call using GDB, and it produced the expected output.
>>
>> Thanks,
>> Florian
>> ---
> 
> LGTM.
> 
> Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
 
Approved as RM for glibc 2.36.

This avoids us calling malloc down the failing path.

>   malloc/malloc.c | 15 +++++----------
>>   1 file changed, 5 insertions(+), 10 deletions(-)
>>
>> diff --git a/malloc/malloc.c b/malloc/malloc.c
>> index 12908b8f97..bd3c76ed31 100644
>> --- a/malloc/malloc.c
>> +++ b/malloc/malloc.c
>> @@ -292,19 +292,14 @@
>>   # define __assert_fail(assertion, file, line, function)            \
>>        __malloc_assert(assertion, file, line, function)
>>   -extern const char *__progname;
>> -
>> -static void
>> +_Noreturn static void
>>   __malloc_assert (const char *assertion, const char *file, unsigned int line,
>>            const char *function)
>>   {
>> -  (void) __fxprintf (NULL, "%s%s%s:%u: %s%sAssertion `%s' failed.\n",
>> -             __progname, __progname[0] ? ": " : "",
>> -             file, line,
>> -             function ? function : "", function ? ": " : "",
>> -             assertion);
>> -  fflush (stderr);
>> -  abort ();
>> +  __libc_message (do_abort, "\
>> +Fatal glibc error: malloc assertion failure in %s: %s\n",
>> +          function, assertion);
>> +  __builtin_unreachable ();
>>   }
>>   #endif
>>   #endif
>>
> 


-- 
Cheers,
Carlos.