From: Bruno Haible <bruno@clisp.org> Date: Sat, 27 Jun 2020 22:40:04 +0000 (+0200) Subject: fatal-signal: Make multithread-safe. X-Git-Tag: v1.0~3953 X-Git-Url: https://gitweb.git.savannah.gnu.org/gitweb/?a=commitdiff_plain;h=447062a6999c2df9cd35d6c4297dc1a55bd39cd7;p=gnulib.git fatal-signal: Make multithread-safe. * lib/fatal-signal.c (at_fatal_signal): Don't free the old actions array. --- diff --git a/ChangeLog b/ChangeLog index 7e046bc402..12dadaaa36 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,8 @@ +2020-06-27 Bruno Haible <bruno@clisp.org> + + fatal-signal: Make multithread-safe. + * lib/fatal-signal.c (at_fatal_signal): Don't free the old actions array. + 2020-06-27 Bruno Haible <bruno@clisp.org> clean-temp: Don't force deletion of temporary files on native Windows. diff --git a/lib/fatal-signal.c b/lib/fatal-signal.c index 975393b4a0..c6f8dacbde 100644 --- a/lib/fatal-signal.c +++ b/lib/fatal-signal.c @@ -239,8 +239,15 @@ at_fatal_signal (action_t action) actions = new_actions; actions_allocated = new_actions_allocated; /* Now we can free the old actions array. */ + /* No, we can't do that. If fatal_signal_handler is running in a + different thread and has already fetched the actions pointer (getting + old_actions) but not yet accessed its n-th element, that thread may + crash when accessing an element of the already freed old_actions + array. */ + #if 0 if (old_actions != static_actions) free (old_actions); + #endif } /* The two uses of 'volatile' in the types above (and ISO C 99 section 5.1.2.3.(5)) ensure that we increment the actions_count only after