From ae74c3b69a08e1de20cb681ec959f3a48af0006a Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 2 Aug 2006 20:17:49 -0700 Subject: [PATCH] Fix force_sig_info() semantics after cleanups Suresh points out that commit b0423a0d9cc836b2c3d796623cd19236bfedfe63 broke the semantics of a synchronous signal like SIGSEGV occurring recursively inside its own handler handler (or, indeed, any other context when the signal was blocked). That was unintentional, and this fixes things up by reinstating the old semantics, but without reverting the cleanups. Cc: Paul E. McKenney Acked-by: Suresh Siddha Signed-off-by: Linus Torvalds --- kernel/signal.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 7fe874d12fae..bfdb5686fa3e 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -791,22 +791,31 @@ specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t) /* * Force a signal that the process can't ignore: if necessary * we unblock the signal and change any SIG_IGN to SIG_DFL. + * + * Note: If we unblock the signal, we always reset it to SIG_DFL, + * since we do not want to have a signal handler that was blocked + * be invoked when user space had explicitly blocked it. + * + * We don't want to have recursive SIGSEGV's etc, for example. */ - int force_sig_info(int sig, struct siginfo *info, struct task_struct *t) { unsigned long int flags; - int ret; + int ret, blocked, ignored; + struct k_sigaction *action; spin_lock_irqsave(&t->sighand->siglock, flags); - if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) { - t->sighand->action[sig-1].sa.sa_handler = SIG_DFL; - } - if (sigismember(&t->blocked, sig)) { - sigdelset(&t->blocked, sig); + action = &t->sighand->action[sig-1]; + ignored = action->sa.sa_handler == SIG_IGN; + blocked = sigismember(&t->blocked, sig); + if (blocked || ignored) { + action->sa.sa_handler = SIG_DFL; + if (blocked) { + sigdelset(&t->blocked, sig); + recalc_sigpending_tsk(t); + } } - recalc_sigpending_tsk(t); ret = specific_send_sig_info(sig, info, t); spin_unlock_irqrestore(&t->sighand->siglock, flags); -- GitLab