From 87801a8fd06db1d654eea3e4f7626ff476a9bdaa Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Thu, 25 Apr 2024 15:00:45 +0200
Subject: [PATCH] CVE-2024-33599: nscd: Stack-based buffer overflow in netgroup
 cache (bug 31677)

Using alloca matches what other caches do.  The request length is
bounded by MAXKEYLEN.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
---
 nscd/netgroupcache.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- glibc-2.31.orig/nscd/netgroupcache.c
+++ glibc-2.31/nscd/netgroupcache.c
@@ -503,12 +503,13 @@ addinnetgrX (struct database_dyn *db, in
       = (struct indataset *) mempool_alloc (db,
 					    sizeof (*dataset) + req->key_len,
 					    1);
-  struct indataset dataset_mem;
   bool cacheable = true;
   if (__glibc_unlikely (dataset == NULL))
     {
       cacheable = false;
-      dataset = &dataset_mem;
+      /* The alloca is safe because nscd_run_worker verfies that
+	 key_len is not larger than MAXKEYLEN.  */
+      dataset = alloca (sizeof (*dataset) + req->key_len);
     }
 
   datahead_init_pos (&dataset->head, sizeof (*dataset) + req->key_len,