The gdbserver_tests/nlcontrolc.vgtest testcase hangs with: glibc-2.32.9000-10.fc34.x86_64 kernel-5.10.0-0.rc0.20201014gitb5fc7a89e58b.41.fc34.x86_64 gdb-9.2-6.fc33.x86_64 The testcase also seems to hang when run by hand. It looks like select () never returns, not even when interrupted with ctrl-c. So it might not actually be a bug in valgrind itself.
*** This bug has been marked as a duplicate of bug 432870 ***