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Re: glibc bug with malloc_stats
- From: GOTO Masanori <gotom at debian dot or dot jp>
- To: Wolfram Gloger <wg at malloc dot de>, libc-alpha at sources dot redhat dot com
- Cc: Peter Jay Salzman <p at dirac dot org>, bug-glibc at gnu dot org
- Date: Thu, 01 May 2003 01:42:12 +0900
- Subject: Re: glibc bug with malloc_stats
- References: <20030429182407.GA16258@dirac.org>
At Tue, 29 Apr 2003 11:24:07 -0700,
Peter Jay Salzman wrote:
> i think this might be a bug:
>
> this program runs fine when FULL is defined and segfaults when it's not.
>
> i've seen this behavior on sarge (glibc 2.3.1), but it doesn't appear to
> happen on glibc 2.2.5 and 2.1.x.
>
> if you have any further questions, please email me since i'm not on the
> glibc-bug mailing list.
Well, it's still segv in the latest cvs.
> #include <stdio.h>
> #include <stdlib.h>
> #include <malloc.h>
> // #define FULL
>
> int main(void)
> {
>
> #ifdef FULL
> char *p = (char *) malloc(20*sizeof(char));
> #endif
>
> malloc_stats();
>
> #ifdef FULL
> free(p);
> malloc_stats();
> #endif
>
> return 0;
> }
This is caused because malloc_arena->next is NULL. The below patch
fixes the problem (Another fix is to initialize next as &main_arena).
Is it OK, Wolfram?
--- malloc/malloc.c 2003-02-02 05:27:15.000000000 +0900
+++ malloc/malloc.c.new 2003-05-01 01:24:27.000000000 +0900
@@ -5108,7 +5108,7 @@
#endif
(void)mutex_unlock(&ar_ptr->mutex);
ar_ptr = ar_ptr->next;
- if(ar_ptr == &main_arena) break;
+ if(ar_ptr == &main_arena || ar_ptr == NULL) break;
}
#if HAVE_MMAP
fprintf(stderr, "Total (incl. mmap):\n");
Regards,
-- gotom