From a3547fd4c165bd6c0c9c9d2643bd61b593f7bbaf Mon Sep 17 00:00:00 2001
From: Oliver Kiddle <opk@zsh.org>
Date: Fri, 31 Oct 2025 10:54:49 +0100
Subject: 54013: add a range check on signal numbers passed to trap

---
 ChangeLog     | 3 +++
 Src/builtin.c | 8 ++++++++
 Src/jobs.c    | 6 +++++-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 9e5110098..b7b58541a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2025-10-31  Oliver Kiddle  <opk@zsh.org>
 
+	* 54013: Src/builtin.c, Src/jobs.c: add a range check on signal
+	numbers passed to trap
+
 	* 54012: Src/subst.c: fix use of out of scope array variable
 
 	* 54007: Src/exec.c, Src/hist.c, Src/init.c, Src/jobs.c, Src/module.c,
diff --git a/Src/builtin.c b/Src/builtin.c
index 5dd4fee01..23067abe1 100644
--- a/Src/builtin.c
+++ b/Src/builtin.c
@@ -7428,6 +7428,14 @@ bin_trap(char *name, char **argv, UNUSED(Options ops), UNUSED(int func))
 	return 1;
     }
 
+    if (!*argv) {
+	if (idigit(*arg) || !strncmp(arg, "SIG", 3))
+	    zwarnnam(name, "undefined signal: %s", arg);
+	else
+	    zwarnnam(name, "signal expected");
+	return 1;
+    }
+
     /* set traps */
     for (; *argv; argv++) {
 	Eprog t;
diff --git a/Src/jobs.c b/Src/jobs.c
index 31938bedd..4905ae925 100644
--- a/Src/jobs.c
+++ b/Src/jobs.c
@@ -3054,7 +3054,11 @@ getsigidx(const char *s)
 
     /* check for a signal specified by number */
     x = atoi(s);
-    if (idigit(*s) && x >= 0)
+    if (idigit(*s) && x >= 0 && (x < VSIGCOUNT
+#if defined(SIGRTMIN) && defined(SIGRTMAX)
+	|| (x >= SIGRTMIN && x <= SIGRTMAX)
+#endif
+	))
 	return SIGIDX(x);
 
     /* search for signal by name */
-- 
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