[PATCH] sigaction should clear all signals on SIG_IGN, not just < 32
While rooting aroung in the signal code trying to understand how to fix the
SIG_IGN ploy (set sig handler to SIG_IGN and flood system with high speed
repeating timers) I came across what, I think, is a problem in sigaction()
in that when processing a SIG_IGN request it flushes signals from 1 to
SIGRTMIN and leaves the rest. Attempt to fix this.
Signed-off-by: George Anzinger <george@mvista.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/signal.h b/include/linux/signal.h
index ea9eff1..b7d0935 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -94,6 +94,23 @@
#endif /* __HAVE_ARCH_SIG_BITOPS */
+static inline int sigisemptyset(sigset_t *set)
+{
+ extern void _NSIG_WORDS_is_unsupported_size(void);
+ switch (_NSIG_WORDS) {
+ case 4:
+ return (set->sig[3] | set->sig[2] |
+ set->sig[1] | set->sig[0]) == 0;
+ case 2:
+ return (set->sig[1] | set->sig[0]) == 0;
+ case 1:
+ return set->sig[0] == 0;
+ default:
+ _NSIG_WORDS_is_unsupported_size();
+ return 0;
+ }
+}
+
#define sigmask(sig) (1UL << ((sig) - 1))
#ifndef __HAVE_ARCH_SIG_SETOPS
diff --git a/kernel/signal.c b/kernel/signal.c
index 9b6fda5..e20724a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -625,6 +625,33 @@
* Returns 1 if any signals were found.
*
* All callers must be holding the siglock.
+ *
+ * This version takes a sigset mask and looks at all signals,
+ * not just those in the first mask word.
+ */
+static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
+{
+ struct sigqueue *q, *n;
+ sigset_t m;
+
+ sigandsets(&m, mask, &s->signal);
+ if (sigisemptyset(&m))
+ return 0;
+
+ signandsets(&s->signal, &s->signal, mask);
+ list_for_each_entry_safe(q, n, &s->list, list) {
+ if (sigismember(mask, q->info.si_signo)) {
+ list_del_init(&q->list);
+ __sigqueue_free(q);
+ }
+ }
+ return 1;
+}
+/*
+ * Remove signals in mask from the pending set and queue.
+ * Returns 1 if any signals were found.
+ *
+ * All callers must be holding the siglock.
*/
static int rm_from_queue(unsigned long mask, struct sigpending *s)
{
@@ -2408,6 +2435,7 @@
do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
{
struct k_sigaction *k;
+ sigset_t mask;
if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
return -EINVAL;
@@ -2455,9 +2483,11 @@
*k = *act;
sigdelsetmask(&k->sa.sa_mask,
sigmask(SIGKILL) | sigmask(SIGSTOP));
- rm_from_queue(sigmask(sig), &t->signal->shared_pending);
+ sigemptyset(&mask);
+ sigaddset(&mask, sig);
+ rm_from_queue_full(&mask, &t->signal->shared_pending);
do {
- rm_from_queue(sigmask(sig), &t->pending);
+ rm_from_queue_full(&mask, &t->pending);
recalc_sigpending_tsk(t);
t = next_thread(t);
} while (t != current);