Our current version of gdb in the v5 toolchain (16.3) has a known bug when setting breakpoints on certain SIMD instructions with RIP-relative reads (31952, 28999, 31481 - these are all basically the same bug). If a user sets a breakpoint on such an instruction and tries to continue after the breakpoint is hit, the RIP-relative read will target the wrong address, typically leading the application to segfault. This is particularly bad for binaries built with -ftrivial-auto-var-init=pattern as they often put one of these SIMD instructions right at the start of functions, so something like b myFunction is all it takes to trigger the bug.

In GDB 17.1, this issue is resolved. We should upgrade to get those fixes. SERVER-116250 upgraded gdb in the toolchain. We have a particular test (crypt_run_tests.sh) that needs to be made to use the new gdb. Currently, it uses the one under /opt/mongodbtoolchain which isn't updated automatically.