Thank you Ivaylo for creating this bug report and helping make Ubuntu better!
I have 2 follow up questions: 1. How often do these segmentation faults occur for you? 2. Have you tried to SSH to the Focal server from multiple other systems? Do you encounter this issue with multiple systems, or is it only observed with one? Could you also run `apport-collect 2043114` in the server that is encountering the seg faults? This will gather debugging information that may be valuable. I see the backtrace has the error nextinuse = <error reading variable nextinuse (Cannot access memory at address 0x5557eba6a008)> I briefly looked into the upstream repository to try and find related commits to this issue and didn't see any commits pop out at me -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to openssh in Ubuntu. https://bugs.launchpad.net/bugs/2043114 Title: sshd segmentation fault on 20.04.6 (focal) Status in openssh package in Ubuntu: Confirmed Bug description: We have a physical server running Ubuntu 20.04.6 LTS (amd64) and openssh-server 1:8.2p1-4ubuntu0.9. Sometimes sshd crashes with a segmentation fault on remote login with key authentication: [193107.651745] sshd[1229630]: segfault at 5557eba6a008 ip 00007f2326a2ca53 sp 00007ffcba40c510 error 4 in libc-2.31.so[7f23269b8000+178000] We’ve changed only the following values in the stock sshd_config file: LogLevel DEBUG PasswordAuthentication no MaxStartups 100:30:100 The server is used for automated software testing, and sometimes our test suite might make a large amount of SSH connections in a short period of time, which seems to be correlated with the crashes. But at the same time, I have to note that the connection count was not near the MaxStartups limit, and we’ve had crashes before adding that setting. Since the backtrace shows the debug logging function in the stack, we’re currently experimenting with using `LogLevel INFO` to try and isolate the issue. I am attaching the backtrace. I could provide the full dump file, although I am hesitant due to the possibility of private keys or other sensitive information leaking. # apt-cache policy openssh-server openssh-server: Installed: 1:8.2p1-4ubuntu0.9 Candidate: 1:8.2p1-4ubuntu0.9 Version table: *** 1:8.2p1-4ubuntu0.9 500 500 http://mirrors.storpool.com/ubuntu/archive focal-updates/main amd64 Packages 500 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages 100 /var/lib/dpkg/status 1:8.2p1-4 500 500 http://mirrors.storpool.com/ubuntu/archive focal/main amd64 Packages To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/2043114/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp