[Pcap] setsockopt(optval) points to uninitialised byte(s)

["Luis MartinGarcia." <luis.mgarc () gmail com>]

Hi,

I've been trying to track down a problem reported by valgrind. When
using pcap_set_filter() on Linux, valgrind complains about a
setsockopt() call that uses a pointer to some uninitialized memory. The
message I get is the following:

==22214== Syscall param socketcall.setsockopt(optval) points to
uninitialised byte(s)
==22214==    at 0x62F774A: setsockopt (syscall-template.S:82)
==22214==    by 0x4E33B85: ??? (in /usr/lib/libpcap.so.1.0.0)
==22214==    by 0x4E33D0D: ??? (in /usr/lib/libpcap.so.1.0.0)
==22214==    by 0x432253: nsock_pcap_set_filter (in /usr/local/bin/nping)
==22214==    by 0x432557: nsock_pcap_open (in /usr/local/bin/nping)
==22214==    by 0x4295FF: ProbeMode::start() (in /usr/local/bin/nping)
==22214==    by 0x40B2E1: main (in /usr/local/bin/nping)

(I've been able to reproduce this message in other tools that use pcap,
so this isn't implementation specific).

Also, I have tracked down the problem to
pcap-linux.c::pcap_setfilter_linux_common(). By adding a simple memset()
call, I am able to get rid of the message. I attach a patch that fixes
this issue. Please, consider integrating it into mainstream.

Regards,

Luis MartinGarcia.

Attachment: pcap_valgrind.diff
Description:

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