https://git.netfilter.org/ipset/commit/?id=851cb04ffee5040f1e0063f77c3fe9bc6245e0fb

From 851cb04ffee5040f1e0063f77c3fe9bc6245e0fb Mon Sep 17 00:00:00 2001
From: Phil Sutter <phil@nwl.cc>
Date: Thu, 27 Jun 2024 10:18:17 +0200
Subject: lib: ipset: Avoid 'argv' array overstepping

The maximum accepted value for 'argc' is MAX_ARGS which matches 'argv'
array size. The maximum allowed array index is therefore argc-1.

This fix will leave items in argv non-NULL-terminated, so explicitly
NULL the formerly last entry after shifting.

Looks like a day-1 bug. Interestingly, this neither triggered ASAN nor
valgrind. Yet adding debug output printing argv entries being copied
did.

Fixes: 1e6e8bd9a62aa ("Third stage to ipset-5")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
--- a/lib/ipset.c
+++ b/lib/ipset.c
@@ -343,9 +343,9 @@ ipset_shift_argv(int *argc, char *argv[], int from)
 
 	assert(*argc >= from + 1);
 
-	for (i = from + 1; i <= *argc; i++)
+	for (i = from + 1; i < *argc; i++)
 		argv[i-1] = argv[i];
-	(*argc)--;
+	argv[--(*argc)] = NULL;
 	return;
 }
 
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