[bug-gawk] length() crash

[miro drahos]

Hi there,
I experienced awk crash (BIG surprise to me), when calling length() on non-existent field.
My version:
GNU Awk 3.1.6
system: bash on Ubuntu Linux 2.6.32-32-generic i686

here is what i did:
//-------------------------------------------------------------------------
$ echo 'one two' | awk '{if(length($3)!=3)$4="000000000000" ; print}' 
*** glibc detected *** awk: double free or corruption (fasttop): 0x08d57d60 ***
======= Backtrace: =========
/lib/tls/i686/cmov/libc.so.6(+0x6b591)[0x2d5591]
/lib/tls/i686/cmov/libc.so.6(+0x6cde8)[0x2d6de8]
/lib/tls/i686/cmov/libc.so.6(cfree+0x6d)[0x2d9ecd]
awk(free_wstr+0x25)[0x80737d5]
awk(get_field+0x1e9)[0x8069e89]
awk(do_print_rec+0xdc)[0x8061a9c]
awk(interpret+0x2cb)[0x8084eeb]
awk(interpret+0x27d)[0x8084e9d]
awk(interpret+0x198)[0x8084db8]
awk(do_input+0x3d)[0x8070e0d]
awk(main+0x1067)[0x8072fc7]
/lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe6)[0x280bd6]
awk[0x804d6f1]
======= Memory map: ========
00110000-0012d000 r-xp 00000000 08:03 260783     /lib/libgcc_s.so.1
0012d000-0012e000 r--p 0001c000 08:03 260783     /lib/libgcc_s.so.1
0012e000-0012f000 rw-p 0001d000 08:03 260783     /lib/libgcc_s.so.1
00266000-00268000 r-xp 00000000 08:03 391399     /lib/tls/i686/cmov/libdl-2.11.1.so
00268000-00269000 r--p 00001000 08:03 391399     /lib/tls/i686/cmov/libdl-2.11.1.so
00269000-0026a000 rw-p 00002000 08:03 391399     /lib/tls/i686/cmov/libdl-2.11.1.so
0026a000-003bd000 r-xp 00000000 08:03 391393     /lib/tls/i686/cmov/libc-2.11.1.so
003bd000-003be000 ---p 00153000 08:03 391393     /lib/tls/i686/cmov/libc-2.11.1.so
003be000-003c0000 r--p 00153000 08:03 391393     /lib/tls/i686/cmov/libc-2.11.1.so
003c0000-003c1000 rw-p 00155000 08:03 391393     /lib/tls/i686/cmov/libc-2.11.1.so
003c1000-003c4000 rw-p 00000000 00:00 0 
00542000-0055d000 r-xp 00000000 08:03 260725     /lib/ld-2.11.1.so
0055d000-0055e000 r--p 0001a000 08:03 260725     /lib/ld-2.11.1.so
0055e000-0055f000 rw-p 0001b000 08:03 260725     /lib/ld-2.11.1.so
00837000-0085b000 r-xp 00000000 08:03 391401     /lib/tls/i686/cmov/libm-2.11.1.so
0085b000-0085c000 r--p 00023000 08:03 391401     /lib/tls/i686/cmov/libm-2.11.1.so
0085c000-0085d000 rw-p 00024000 08:03 391401     /lib/tls/i686/cmov/libm-2.11.1.so
00f7f000-00f80000 r-xp 00000000 00:00 0          [vdso]
08048000-08095000 r-xp 00000000 08:03 132997     /usr/bin/gawk
08095000-08096000 r--p 0004c000 08:03 132997     /usr/bin/gawk
08096000-08097000 rw-p 0004d000 08:03 132997     /usr/bin/gawk
08097000-0809c000 rw-p 00000000 00:00 0 
08d56000-08d77000 rw-p 00000000 00:00 0          [heap]
b7500000-b7521000 rw-p 00000000 00:00 0 
b7521000-b7600000 ---p 00000000 00:00 0 
b76e6000-b7804000 r--p 00000000 08:03 392219     /usr/lib/locale/en_US.utf8/LC_COLLATE
b7804000-b7843000 r--p 00000000 08:03 392480     /usr/lib/locale/en_US.utf8/LC_CTYPE
b7843000-b7845000 rw-p 00000000 00:00 0 
b784f000-b7850000 r--p 00000000 08:03 392307     /usr/lib/locale/en_US.utf8/LC_TIME
b7850000-b7851000 r--p 00000000 08:03 392342     /usr/lib/locale/en_US.utf8/LC_NUMERIC
b7851000-b7852000 r--p 00000000 08:03 392310     /usr/lib/locale/en_US.utf8/LC_MESSAGES/SYS_LC_MESSAGES
b7852000-b7859000 r--s 00000000 08:03 138369     /usr/lib/gconv/gconv-modules.cache
b7859000-b785b000 rw-p 00000000 00:00 0 
bfbfa000-bfc0f000 rw-p 00000000 00:00 0          [stack]
Aborted
//-------------------------------------------------------------------------------------

Thank you very much
Miro Drahos