Description of problem:
Summary say it all

Version-Release number of selected component (if applicable):
glibc-2.7-2

How reproducible:
Easily

Steps to Reproduce:

The failed program:
#include <stdio.h>

main()
{
  char *path = NULL, *line;
  int nbargs;

  line = " ";
  nbargs = sscanf (line, "%as", &path);
  
  printf("nbargs %d\n", nbargs);
}

1. gcc -o t t.c
2. ./t
3.
  
Actual results:
*** glibc detected *** ./t: double free or corruption (out): 0xbfc4e1e0 ***
======= Backtrace: =========
/lib/libc.so.6[0xcefac1]
/lib/libc.so.6(cfree+0x90)[0xcf30f0]
/lib/libc.so.6(_IO_vfscanf+0x906)[0xcd0b66]
/lib/libc.so.6(vsscanf+0x91)[0xce10c1]
/lib/libc.so.6(_IO_sscanf+0x2e)[0xcdbdae]
./t[0x804842d]
/lib/libc.so.6(__libc_start_main+0xe0)[0xc9c390]
./t[0x8048341]
======= Memory map: ========
00110000-00111000 r-xp 00110000 00:00 0          [vdso]
001bb000-001d6000 r-xp 00000000 fd:00 6876214    /lib/ld-2.7.so
001d6000-001d7000 r-xp 0001a000 fd:00 6876214    /lib/ld-2.7.so
001d7000-001d8000 rwxp 0001b000 fd:00 6876214    /lib/ld-2.7.so
00c86000-00dd9000 r-xp 00000000 fd:00 6876215    /lib/libc-2.7.so
00dd9000-00ddb000 r-xp 00153000 fd:00 6876215    /lib/libc-2.7.so
00ddb000-00ddc000 rwxp 00155000 fd:00 6876215    /lib/libc-2.7.so
00ddc000-00ddf000 rwxp 00ddc000 00:00 0 
04ca9000-04cb4000 r-xp 00000000 fd:00 6876239    /lib/libgcc_s-4.1.2-20070925.so.1
04cb4000-04cb5000 rwxp 0000a000 fd:00 6876239    /lib/libgcc_s-4.1.2-20070925.so.1
08048000-08049000 r-xp 00000000 fd:00 6710944    /root/t
08049000-0804a000 rw-p 00000000 fd:00 6710944    /root/t
08181000-081a2000 rw-p 08181000 00:00 0 
b7e00000-b7e21000 rw-p b7e00000 00:00 0 
b7e21000-b7f00000 ---p b7e21000 00:00 0 
b7faa000-b7fac000 rw-p b7faa000 00:00 0 
bfc3a000-bfc4f000 rw-p bffea000 00:00 0          [stack]
Aborted


Expected results:
"nbargs -1"

Additional info:

Known to work on FC-6, F-7, glibc-2.6 (powerpc port).