Note that this will consistently fail alignment checks on architectures which require alignment, because the initial buffer is allocated with reasonable alignment (32bit) but the ethernet header is 14 bytes long, so the TCP header fields will always be unaligned within the buffer.
On Wed, Apr 13, 2022 at 01:20:49PM -0700, Steve Langasek wrote: > Here is a backtrace of the armhf SIGBUS. > > Note that not all ARM implementations return SIGBUS which is probably why > this was not reproducible on the porter machine. > > # gdb --args pktanon -c /usr/share/doc/pktanon/examples/profiles/profile.xml > ./profiles/sample.pcap ./out.pcap > [...] > Reading symbols from pktanon... > Reading symbols from > /usr/lib/debug/.build-id/af/1ac53f46ae133c8898358966960cba95ac7a70.debug... > (gdb) run > Starting program: /usr/bin/pktanon -c > /usr/share/doc/pktanon/examples/profiles/profile.xml ./profiles/sample.pcap > ./out.pcap > [Thread debugging using libthread_db enabled] > Using host libthread_db library "/lib/arm-linux-gnueabihf/libthread_db.so.1". > ----------------------------------------------- > pktanon --- profile-based traffic anonymization > ----------------------------------------------- > initializing PktAnon, configuration = > /usr/share/doc/pktanon/examples/profiles/profile.xml > unknown element: pktanon-config: 37 > unknown element: anonymizations: 102 > istream: opened file ./profiles/sample.pcap > ostream: opened output file ./out.pcap > initialized > > Program received signal SIGBUS, Bus error. > pktanon::TcpPacketTransformation::transform (this=<optimized out>, > source_buffer=<optimized out>, destination_buffer=0xfffef35a > "\212y\262X\335\300l\221", max_packet_length=40) at > transformations/TcpPacketTransformation.cpp:88 > 88 hton32 (output_header->ack_num); > (gdb) bt > #0 pktanon::TcpPacketTransformation::transform (this=<optimized out>, > source_buffer=<optimized out>, > destination_buffer=0xfffef35a "\212y\262X\335\300l\221", > max_packet_length=40) at transformations/TcpPacketTransformation.cpp:88 > #1 0x0040b77c in pktanon::IPv4PacketTransformation::transform > (this=0x4b4eb0, > source_buffer=<optimized out>, destination_buffer=0xfffef346 "E", > max_packet_length=<optimized out>) > at transformations/IPv4PacketTransformation.cpp:153 > #2 0x0040af64 in pktanon::EthernetPacketTransformation::transform ( > this=0x4ad780, source_buffer=<optimized out>, > destination_buffer=0xfffef338 > "\376\212\a\213\001\254\303\341\372DI\355\b", max_packet_length=74) at > transformations/EthernetPacketTransformation.cpp:53 > #3 0x00416862 in pktanon::transform_packet (stats=..., > packet_len=<optimized out>, > transformed_packet=0xfffef338 > "\376\212\a\213\001\254\303\341\372DI\355\b", original_packet=0xfffef438 "", > record_header=...) at Utils.h:26 > #4 pktanon::IstreamInput::read_packets (this=0x4b3ce0) > at IstreamRecordsHandler.cpp:121 > #5 0x00415130 in pktanon::PktAnonRuntime::run () at PktAnonRuntime.cpp:37 > #6 0x00405bfa in main (argc=<optimized out>, argv=<optimized out>) > at src/Main.cpp:73 > (gdb) > > So, this is trying to do an hton32() operation on a field that is not 4-byte > aligned. > > -- > Steve Langasek Give me a lever long enough and a Free OS > Debian Developer to set it on, and I can move the world. > Ubuntu Developer https://www.debian.org/ > slanga...@ubuntu.com vor...@debian.org -- Steve Langasek Give me a lever long enough and a Free OS Debian Developer to set it on, and I can move the world. Ubuntu Developer https://www.debian.org/ slanga...@ubuntu.com vor...@debian.org
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