On Fri, Jan 16, 2026 at 1:38 AM Filippo Carletti <[email protected]> wrote: > > Repost from: https://forum.openwrt.org/t/pppoe-crash-fatal-signal-4/245299 > > I’m looking for advice from a developer. > > Issue: I can’t connect to the ISP using PPPoE, because pppd crashes. See logs: > > Thu Jan 15 18:21:30 2026 daemon.notice netifd: Interface 'eolo' is > setting up now > Thu Jan 15 18:21:30 2026 daemon.info pppd[11758]: Plugin pppoe.so loaded. > Thu Jan 15 18:21:30 2026 daemon.info pppd[11758]: PPPoE plugin from pppd 2.5.2 > Thu Jan 15 18:21:30 2026 daemon.notice pppd[11758]: pppd 2.5.2 started > by root, uid 0 > Thu Jan 15 18:21:30 2026 daemon.info pppd[11758]: PPP session is 56000 > Thu Jan 15 18:21:30 2026 daemon.warn pppd[11758]: Connected to > 52:54:00:93:DC:01 via interface eth2 > Thu Jan 15 18:21:30 2026 daemon.info pppd[11758]: Using interface pppoe-eolo > Thu Jan 15 18:21:30 2026 daemon.notice pppd[11758]: Connect: > pppoe-eolo <--> eth2 > Thu Jan 15 18:21:30 2026 daemon.info ModemManager[11766]: hotplug: add > network interface pppoe-eolo: event processed > Thu Jan 15 18:21:31 2026 daemon.err pppd[11758]: Fatal signal 4 > Thu Jan 15 18:21:31 2026 daemon.info ModemManager[11793]: hotplug: > remove network interface pppoe-eolo: event processed > Thu Jan 15 18:21:31 2026 daemon.info pppd[11758]: Exit. > > OPENWRT_RELEASE="OpenWrt 25.12.0-rc2 r32429-d76c64ad00" (pppd version > 2.5.2), but I tested also 24.10 (2.5.1). OPENWRT_ARCH="x86_64" > > Compiling pppd with debug symbols and using gbd, I think I’ve > identified the problem with the long list of LCP options: > > Program received signal SIGILL, Illegal instruction. > memcpy (__n=<optimized out>, __os=<optimized out>, __od=<optimized > out>, __od=<optimized out>, __os=<optimized out>, __n=<optimized out>) > at > ../../../../../../staging_dir/toolchain-x86_64_gcc-13.3.0_musl/include/fortify/string.h:50 > warning: 50 > ../../../../../../staging_dir/toolchain-x86_64_gcc-13.3.0_musl/include/fortify/string.h: > No such file or directory > (gdb) bt > #0 memcpy (__n=<optimized out>, __os=<optimized out>, __od=<optimized > out>, __od=<optimized out>, __os=<optimized out>, __n=<optimized out>) > at > ../../../../../../staging_dir/toolchain-x86_64_gcc-13.3.0_musl/include/fortify/string.h:50 > #1 lcp_reqci (f=<optimized out>, inp=0x5555555b1368 <inpacket_buf+8> > "\001\004\005\324\002\006", lenp=0x7fffffffe89c, reject_if_disagree=0) > at > /home/build/openwrt/build_dir/target-x86_64_musl/linux-x86_64/ppp-default/ppp-2.5.1/pppd/lcp.c:1804 > > I disabled FORTIFY_SOURCE and pppd connected. > > I captured a pcap of both a successful and failed connection: patched > pppd refused the first LCP options packet and the ISP proceeded with a > different list, reaching the connected state. Connection remains > stable. > > Given that disabling FORTIFY_SOURCE is not an option, how can we fix the > issue? Does this help? https://github.com/ppp-project/ppp/commit/7060ac7c505e685bebca05eb14fa1d9550364051 > > Note: Using scapy and the pcap I can reproduce the crash on a couple > of virtual machines. > > -- > Filippo > > _______________________________________________ > openwrt-devel mailing list > [email protected] > https://lists.openwrt.org/mailman/listinfo/openwrt-devel
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