[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 (file)
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -94,6 +94,23 @@ static inline int sigfindinword(unsigned long word)
 
 #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 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -620,6 +620,33 @@ void signal_wake_up(struct task_struct *t, int resume)
                kick_process(t);
 }
 
+/*
+ * Remove signals in mask from the pending set and queue.
+ * 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.
@@ -2408,6 +2435,7 @@ int
 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 @@ do_sigaction(int sig, const struct k_sigaction *act, struct k_sigaction *oact)
                        *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);