MFC r270321:

Ensure that sigaction flags for signal, which disposition is reset to
ignored or default, are not leaking.

MFC r270504:
Revert the handling of all siginfo sa_flags except SA_SIGINFO to the
pre-r270321 state.

1 files changed, 44 insertions, 33 deletions

diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 11e0fdb..45e12c4 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -626,6 +626,20 @@ sig_ffs(sigset_t *set)
 	return (0);
 }
 
+static bool
+sigact_flag_test(struct sigaction *act, int flag)
+{
+
+	/*
+	 * SA_SIGINFO is reset when signal disposition is set to
+	 * ignore or default.  Other flags are kept according to user
+	 * settings.
+	 */
+	return ((act->sa_flags & flag) != 0 && (flag != SA_SIGINFO ||
+	    ((__sighandler_t *)act->sa_sigaction != SIG_IGN &&
+	    (__sighandler_t *)act->sa_sigaction != SIG_DFL)));
+}
+
 /*
  * kern_sigaction
  * sigaction
@@ -688,7 +702,7 @@ kern_sigaction(td, sig, act, oact, flags)
 
 		ps->ps_catchmask[_SIG_IDX(sig)] = act->sa_mask;
 		SIG_CANTMASK(ps->ps_catchmask[_SIG_IDX(sig)]);
-		if (act->sa_flags & SA_SIGINFO) {
+		if (sigact_flag_test(act, SA_SIGINFO)) {
 			ps->ps_sigact[_SIG_IDX(sig)] =
 			    (__sighandler_t *)act->sa_sigaction;
 			SIGADDSET(ps->ps_siginfo, sig);
@@ -696,19 +710,19 @@ kern_sigaction(td, sig, act, oact, flags)
 			ps->ps_sigact[_SIG_IDX(sig)] = act->sa_handler;
 			SIGDELSET(ps->ps_siginfo, sig);
 		}
-		if (!(act->sa_flags & SA_RESTART))
+		if (!sigact_flag_test(act, SA_RESTART))
 			SIGADDSET(ps->ps_sigintr, sig);
 		else
 			SIGDELSET(ps->ps_sigintr, sig);
-		if (act->sa_flags & SA_ONSTACK)
+		if (sigact_flag_test(act, SA_ONSTACK))
 			SIGADDSET(ps->ps_sigonstack, sig);
 		else
 			SIGDELSET(ps->ps_sigonstack, sig);
-		if (act->sa_flags & SA_RESETHAND)
+		if (sigact_flag_test(act, SA_RESETHAND))
 			SIGADDSET(ps->ps_sigreset, sig);
 		else
 			SIGDELSET(ps->ps_sigreset, sig);
-		if (act->sa_flags & SA_NODEFER)
+		if (sigact_flag_test(act, SA_NODEFER))
 			SIGADDSET(ps->ps_signodefer, sig);
 		else
 			SIGDELSET(ps->ps_signodefer, sig);
@@ -909,14 +923,31 @@ siginit(p)
 	PROC_LOCK(p);
 	ps = p->p_sigacts;
 	mtx_lock(&ps->ps_mtx);
-	for (i = 1; i <= NSIG; i++)
-		if (sigprop(i) & SA_IGNORE && i != SIGCONT)
+	for (i = 1; i <= NSIG; i++) {
+		if (sigprop(i) & SA_IGNORE && i != SIGCONT) {
 			SIGADDSET(ps->ps_sigignore, i);
+		}
+	}
 	mtx_unlock(&ps->ps_mtx);
 	PROC_UNLOCK(p);
 }
 
 /*
+ * Reset specified signal to the default disposition.
+ */
+static void
+sigdflt(struct sigacts *ps, int sig)
+{
+
+	mtx_assert(&ps->ps_mtx, MA_OWNED);
+	SIGDELSET(ps->ps_sigcatch, sig);
+	if ((sigprop(sig) & SA_IGNORE) != 0 && sig != SIGCONT)
+		SIGADDSET(ps->ps_sigignore, sig);
+	ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
+	SIGDELSET(ps->ps_siginfo, sig);
+}
+
+/*
  * Reset signals for an exec of the specified process.
  */
 void
@@ -937,13 +968,9 @@ execsigs(struct proc *p)
 	mtx_lock(&ps->ps_mtx);
 	while (SIGNOTEMPTY(ps->ps_sigcatch)) {
 		sig = sig_ffs(&ps->ps_sigcatch);
-		SIGDELSET(ps->ps_sigcatch, sig);
-		if (sigprop(sig) & SA_IGNORE) {
-			if (sig != SIGCONT)
-				SIGADDSET(ps->ps_sigignore, sig);
+		sigdflt(ps, sig);
+		if ((sigprop(sig) & SA_IGNORE) != 0)
 			sigqueue_delete_proc(p, sig);
-		}
-		ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
 	}
 	/*
 	 * Reset stack state to the user stack.
@@ -1901,16 +1928,8 @@ trapsignal(struct thread *td, ksiginfo_t *ksi)
 			SIGADDSET(mask, sig);
 		kern_sigprocmask(td, SIG_BLOCK, &mask, NULL,
 		    SIGPROCMASK_PROC_LOCKED | SIGPROCMASK_PS_LOCKED);
-		if (SIGISMEMBER(ps->ps_sigreset, sig)) {
-			/*
-			 * See kern_sigaction() for origin of this code.
-			 */
-			SIGDELSET(ps->ps_sigcatch, sig);
-			if (sig != SIGCONT &&
-			    sigprop(sig) & SA_IGNORE)
-				SIGADDSET(ps->ps_sigignore, sig);
-			ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
-		}
+		if (SIGISMEMBER(ps->ps_sigreset, sig))
+			sigdflt(ps, sig);
 		mtx_unlock(&ps->ps_mtx);
 	} else {
 		/*
@@ -2853,16 +2872,8 @@ postsig(sig)
 		kern_sigprocmask(td, SIG_BLOCK, &mask, NULL,
 		    SIGPROCMASK_PROC_LOCKED | SIGPROCMASK_PS_LOCKED);
 
-		if (SIGISMEMBER(ps->ps_sigreset, sig)) {
-			/*
-			 * See kern_sigaction() for origin of this code.
-			 */
-			SIGDELSET(ps->ps_sigcatch, sig);
-			if (sig != SIGCONT &&
-			    sigprop(sig) & SA_IGNORE)
-				SIGADDSET(ps->ps_sigignore, sig);
-			ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
-		}
+		if (SIGISMEMBER(ps->ps_sigreset, sig))
+			sigdflt(ps, sig);
 		td->td_ru.ru_nsignals++;
 		if (p->p_sig == sig) {
 			p->p_code = 0;