$ gdb src/grep core.1430
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Reading symbols from /home/staff/b/grep-2.18/src/grep...done.
[New LWP 1430]

warning: Can't read pathname for load map: Input/output error.
Core was generated by `src/grep -P .?ma test-image.png'.
Program terminated with signal 11, Segmentation fault.
#0  0x001612ca in match (eptr=0x9a24fff <Address 0x9a24fff out of bounds>, ecode=0x9a25e65 "\035m\035ax",
    mstart=0x9a26e9d "\272\374;\017\233\323\230:\364\005+\373a&\367\032X\304\216 \342y\274\301\357\361\005",
    offset_top=2, md=0xbfe18a64, eptrb=0x0, rdepth=0) at pcre_exec.c:5943
5943              BACKCHAR(eptr);
(gdb) bt
#0  0x001612ca in match (eptr=0x9a24fff <Address 0x9a24fff out of bounds>, ecode=0x9a25e65 "\035m\035ax",
    mstart=0x9a26e9d "\272\374;\017\233\323\230:\364\005+\373a&\367\032X\304\216 \342y\274\301\357\361\005",
    offset_top=2, md=0xbfe18a64, eptrb=0x0, rdepth=0) at pcre_exec.c:5943
#1  0x0016308a in pcre_exec (argument_re=0x9a25e28, extra_data=0x9a25e78,
    subject=0x9a26e9d "\272\374;\017\233\323\230:\364\005+\373a&\367\032X\304\216 \342y\274\301\357\361\005",
    length=101, start_offset=0, options=8192, offsets=0xbfe18bdc, offsetcount=300) at pcre_exec.c:6941
#2  0x0805a472 in Pexecute (buf=0x9a26000 "\211PNG\r\n\032\n", size=6568, match_size=0xbfe19114, start_ptr=0x0)
    at pcresearch.c:174
#3  0x0804ba07 in do_execute (buf=0x9a26000 "\211PNG\r\n\032\n", size=6568, match_size=0xbfe19114, start_ptr=0x0)
    at grep.c:1073
#4  0x0804bc98 in grepbuf (beg=0x9a26000 "\211PNG\r\n\032\n",
    lim=0x9a279a8 "\217\222(\016\001c\025R\221c\233S\250\327\177m\002\344Q\022\362$\320\066\376\327\245{\f\035D\001\260\251\326a\247{T\200_\bj8\274") at grep.c:1109
#5  0x0804bfb3 in grep (fd=3, st=0xbfe19200) at grep.c:1220
#6  0x0804c9ab in grepdesc (desc=3, command_line=1) at grep.c:1474
#7  0x0804c650 in grepfile (dirdesc=-100, name=0xbfe19889 "test-image.png", follow=1, command_line=1) at grep.c:1375
#8  0x0804cc22 in grep_command_line_arg (arg=0xbfe19889 "test-image.png") at grep.c:1526
#9  0x0804e358 in main (argc=4, argv=0xbfe194a4) at grep.c:2362