signal mask not reset on exec

[John Sullivan]

Seen in qemu-1.0 under 12.04, but AFAICT from current git it hasn't changed.

./main-loop.c:qemu_signal_init blocks SIGALRM so it can be handled via signalfd.

./net/tap.c:launch_script does not reset the signal mask before the execv() call, and signal masks are inherited. So the script is run with SIGALRM blocked (as can be seen in /proc/$$/status, "SigBlk: 0000000000002000"). One reasonable example of where this bites is an interface up script that calls ping with a timeout to give things a chance to settle down before continuing, but abort if this doesn't happen within a reasonable time). Since ping uses SIGALRM for the timeout, this now never terminates.

qemu-0.14 didn't block SIGALRM, so such scripts worked fine there.

[Thomas Huth (th-huth)]

Triaging old bug tickets... can you still reproduce this issue with the latest version of QEMU? Or could we close this ticket nowadays?

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]