From 8a7aaf25d064232815178d110b05f8a031db5170 Mon Sep 17 00:00:00 2001
From: Maria Matejka <mq@ucw.cz>
Date: Mon, 23 Dec 2024 17:05:09 +0100
Subject: [PATCH] OSPF: fix stack overflow with too many routes

We should not use alloca() in a loop.

This bug happened around 100k routes in OSPF, which
supposedly nobody runs in production.
---
 proto/ospf/rt.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/proto/ospf/rt.c b/proto/ospf/rt.c
index d7753ce0a..6e1544ba5 100644
--- a/proto/ospf/rt.c
+++ b/proto/ospf/rt.c
@@ -2068,9 +2068,14 @@ again1:
 	.pref = p->p.main_channel->preference,
       };
 
+      struct {
+	ea_list l;
+	eattr a[4];
+      } eal;
+
       if (reload || ort_changed(nf, &a0))
       {
-	a0.eattrs = alloca(sizeof(ea_list) + 4 * sizeof(eattr));
+	a0.eattrs = &eal.l;
 	memset(a0.eattrs, 0, sizeof(ea_list));
 
 	nf->old_metric1 = nf->n.metric1;
-- 
2.47.2