Package: openssh-server Version: 1:8.4p1-5 Severity: important Dear Maintainer,
I just noticed many many sshd segfaults listed in /var/log/kern.log. There are two versions. They look like this: sshd: segfault at 7ffd4a0c4a90 ip 00007fa42b77d817 sp 00007ffd4a0c4a60 error 6 in libc-2.28.so[7fa42b741000+148000] sshd: segfault at 7fff0f6b7368 ip 00007fb1d004d0ff sp 00007fff0f6b7370 error 6 in libwrap.so.0.7.6[7fb1d004c000+5000] The hex addresses are different each time, but the rest is the same. It happens everytime there's an incoming ssh connection attempt via IPv6 when the IPv6 address isn't listed in /etc/hosts.allow. There are many because it's from a cronned backup job. I am using /etc/hosts.allow for sshd and have a mixture of IPv4 and IPv6 addresses in it. The remote host in question used to connect via IPv4, but it recently got itself an IPv6 address and started using that. But that was more than 4 days ago when the segfaults started. I don't know of anything that changed on that day. When I added the IPv6 address to /etc/hosts.allow, the segfaults stopped and the connections worked. In case it matters, I'm putting IPv6 addresses between [] without a /prefixlen in /etc/hosts.allow. Strangely, the log messages started appearing 2 days before I upgraded to debian-11. And the libc-bin version in the logs is libc-2.28 which is the version for debian-10, but I'm still getting the segfaults 2 days after upgrading to debian-11 where the libc-bin version is 2.31. The libwrap version in the logs seems to match the current one (libwrap0:amd64 7.6.q-31). I can't find the version for debian-10. Perhapas it was 7.6 as well. I did reboot after the upgrade (or did I?), so I don't understand why there are still log messages mentioning the old libc version. I've rebooted again, and the logs now mention the current debian11 package versions: sshd[1086]: segfault at 7fff615eaec8 ip 00007ff2a586f42f sp 00007fff615eaed0 error 6 in libwrap.so.0.7.6[7ff2a586e000+5000] sshd[1094]: segfault at 7ffcd3ff6f08 ip 00007f18d4f5dac7 sp 00007ffcd3ff6ed0 error 6 in libc-2.31.so[7f18d4f2a000+14b000] sshd[1099]: segfault at 7ffe04ff4b78 ip 00007f204bb55ac7 sp 00007ffe04ff4b40 error 6 in libc-2.31.so[7f204bb22000+14b000] So it looks like it affects both debian10 and debian11. And adding the IPv6 back into /etc/hosts.allow fixes it in both. It's possible that this bugreport should be for the libwrap0 package. I'm not sure. Perhaps you'll be able to determine that. cheers, raf -- System Information: Debian Release: 11.0 APT prefers stable-security APT policy: (500, 'stable-security'), (500, 'stable') Architecture: amd64 (x86_64) Kernel: Linux 5.10.0-8-amd64 (SMP w/1 CPU thread) Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8), LANGUAGE not set Shell: /bin/sh linked to /usr/bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled Versions of packages openssh-server depends on: ii adduser 3.118 ii debconf [debconf-2.0] 1.5.77 ii dpkg 1.20.9 ii libaudit1 1:3.0-2 ii libc6 2.31-13 ii libcom-err2 1.46.2-2 ii libcrypt1 1:4.4.18-4 ii libgssapi-krb5-2 1.18.3-6 ii libkrb5-3 1.18.3-6 ii libpam-modules 1.4.0-9 ii libpam-runtime 1.4.0-9 ii libpam0g 1.4.0-9 ii libselinux1 3.1-3 ii libssl1.1 1.1.1k-1 ii libsystemd0 247.3-6 ii libwrap0 7.6.q-31 ii lsb-base 11.1.0 ii openssh-client 1:8.4p1-5 ii openssh-sftp-server 1:8.4p1-5 ii procps 2:3.3.17-5 ii runit-helper 2.10.3 ii ucf 3.0043 ii zlib1g 1:1.2.11.dfsg-2 Versions of packages openssh-server recommends: pn default-logind | logind | libpam-systemd <none> ii ncurses-term 6.2+20201114-2 pn xauth <none> Versions of packages openssh-server suggests: pn molly-guard <none> pn monkeysphere <none> pn ssh-askpass <none> pn ufw <none> -- debconf information excluded
