On Mon, Aug 25, 2014 at 10:39:59PM -0500, Vladimir Támara Patiño wrote: > Using tcpdump in a firewall with 5.5 (also happens with 5.4 and I guess with > current) and certain addres of the LAN I got always a segfault.
Nope, already fixed in the upcomming 5.6 release and -current. http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/asr/gethostnamadr_async.c#rev1.29 (Should be easily adaptable to 5.5 if it's not already applies cleanly.) In general it's greatly appreciated if you could test on -current, too. Just by chance I remembered this one. Next time you might not get so lucky and at worst waste valuable developer time. Thanks, Florian > > It is a bug within the function gethostbyaddr. It can be reproduced > with the minimal test program available at: > http://openbsd.7691.n7.nabble.com/problem-with-gethostbyaddr-on-OBSD-5-4-td242329.html > and the following steps: > > 1. Create a entry in /etc/hosts with IP address but without name, for example: > echo 192.168.1.89 >> /etc/hosts > 2. Compile the test program of the link > cc -o gethostbyaddr gethostbyaddr.c > 3. Run de test program with the address added to /etc/hosts without name: > ./gethostbyaddr 192.168.1.89 > > Using gdb to trace the problem I got: > > Loaded symbols for /home/vtamara/comp/OpenBSD/buggethostbyaddr/gethostbyaddr > Reading symbols from /usr/lib/libc.so.73.1...done. > Loaded symbols for /usr/lib/libc.so.73.1 > Reading symbols from /usr/libexec/ld.so...done. > Loaded symbols for /usr/libexec/ld.so > #0 0x000018d69baa2ba2 in strlen (str=0x0) > at /usr/src/lib/libc/string/strlen.c:43 > 43 for (s = str; *s; ++s) > (gdb) bt > #0 0x000018d69baa2ba2 in strlen (str=0x0) > at /usr/src/lib/libc/string/strlen.c:43 > #1 0x000018d69ba68d91 in hostent_set_cname (h=0x18d69bee9800, > name=0x0, isdname=Variable "isdname" is not available. > ) at /usr/src/lib/libc/asr/gethostnamadr_async.c:579 > #2 0x000018d69ba696bd in gethostnamadr_async_run > (as=0x18d6957d3d00, ar=0x7f7fffff69c0) at > /usr/src/lib/libc/asr/gethostnamadr_async.c:451 > #3 0x000018d69ba8078c in asr_async_run (as=0x18d6957d3d00, ar=0x7f7fffff69c0) > at /usr/src/lib/libc/asr/asr.c:197 > #4 0x000018d69ba8085b in asr_async_run_sync (as=0x18d6957d3d00, > ar=0x7f7fffff69c0) at /usr/src/lib/libc/asr/asr.c:222 > #5 0x000018d69ba68824 in gethostbyaddr (addr=0x7f7fffff6a80, len=4, af=2) > at /usr/src/lib/libc/asr/gethostnamadr.c:179 > #6 0x000018d495400fbb in main () > from /home/vtamara/comp/OpenBSD/buggethostbyaddr/gethostbyaddr > > As shown hostent_set_cname receives name in NULL and tries to call > strlen with it, a simple patch is attached. > > -- > Dios, gracias por tu amor infinito. > -- Vladimir Támara Patiño. http://vtamara.pasosdeJesus.org/ > http://www.pasosdejesus.org/dominio_publico_colombia.html > > diff -ruN src55-orig/lib/libc/asr/gethostnamadr_async.c > src/lib/libc/asr/gethostnamadr_async.c > --- src55-orig/lib/libc/asr/gethostnamadr_async.c Wed Feb 26 15:00:08 2014 > +++ src/lib/libc/asr/gethostnamadr_async.c Mon Aug 25 15:34:18 2014 > @@ -565,7 +565,7 @@ > char buf[MAXDNAME]; > size_t n; > > - if (h->h.h_name) > + if (h->h.h_name || name == NULL) > return (-1); > > if (isdname) { -- I'm not entirely sure you are real.
