netfilter: nfnetlink_hook: fix check for snprintf() overflow

The kernel version of snprintf() can't return negatives. The "ret > (int)sizeof(sym)" check is off by one because and it should be >=. Finally, we need to set a negative error code. Fixes: e2cf17d ("netfilter: add new hook nfnl subsystem") Signed-off-by: Dan Carpenter <[email protected]> Reviewed-by: Florian Westphal <[email protected]> Signed-off-by: Pablo Neira Ayuso <[email protected]>
chewitt · Jun 21, 2021 · 24610ed · 24610ed
1 parent 3078d96
commit 24610ed
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/net/netfilter/nfnetlink_hook.c b/net/netfilter/nfnetlink_hook.c
@@ -126,8 +126,10 @@ static int nfnl_hook_dump_one(struct sk_buff *nlskb,
 
 #ifdef CONFIG_KALLSYMS
 	ret = snprintf(sym, sizeof(sym), "%ps", ops->hook);
-	if (ret < 0 || ret > (int)sizeof(sym))
+	if (ret >= sizeof(sym)) {
+		ret = -EINVAL;
 		goto nla_put_failure;
+	}
 
 	module_name = strstr(sym, " [");
 	if (module_name) {