--- sys/libkern/arc4random.c.orig	2026-10-17 14:02:28.000000000 +0000
+++ sys/libkern/arc4random.c	2026-10-17 14:08:00.000000000 +0000
@@ -143,18 +143,34 @@
 {
 	struct arc4_data *d = arc4_data_pcpu[mycpuid];
 	uint8_t *p = ptr;
+	size_t chunk;
 
 #if 0
 	/* No one call this function in ISR/ithread. */
 	crit_enter();
 #endif
 
-	if (++(d->arc4_numruns) > ARC4_MAXRUNS ||
-	    time_uptime > d->arc4_nextreseed)
-		arc4_randomstir(d);
+	/*
+	 * Charge the emitted keystream against the reseed budget (one
+	 * run per 4 bytes, matching karc4random()) and cap the number
+	 * of bytes generated under a single key, instead of charging
+	 * one run per CALL and streaming an unbounded number of bytes
+	 * from one RC4 key on a large request.
+	 */
+	while (len) {
+		chunk = len;
+		if (chunk > (size_t)ARC4_MAXRUNS * 4)
+			chunk = (size_t)ARC4_MAXRUNS * 4;
 
-	while (len--)
-		*p++ = arc4_randbyte(d);
+		if (++(d->arc4_numruns) > ARC4_MAXRUNS ||
+		    time_uptime > d->arc4_nextreseed)
+			arc4_randomstir(d);
+
+		d->arc4_numruns += (int)(chunk / 4);
+		len -= chunk;
+		while (chunk--)
+			*p++ = arc4_randbyte(d);
+	}
 
 #if 0
 	crit_exit();