grub: add a fix for a possible NULL dereference

This fix removes a possible NULL pointer dereference in grub
networking code. It is a part of a security series [1].

[1] https://lists.gnu.org/archive/html/grub-devel/2021-03/msg00007.html

(From OE-Core rev: 5e62b476b541d3803e537f2228a264224b72cf81)

Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-bsp/grub/files/0002-net-net-Fix-possible-dereference-to-of-a-NULL-pointe.patch

@@ -0,0 +1,39 @@
+From f216a75e884ed5e4e94bf86965000dde51148f94 Mon Sep 17 00:00:00 2001
+From: Darren Kenny <darren.kenny@oracle.com>
+Date: Fri, 27 Nov 2020 15:10:26 +0000
+Subject: [PATCH] net/net: Fix possible dereference to of a NULL pointer
+
+It is always possible that grub_zalloc() could fail, so we should check for
+a NULL return. Otherwise we run the risk of dereferencing a NULL pointer.
+
+Fixes: CID 296221
+
+Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
+Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
+
+Upstream-Status: Backport [https://git.savannah.gnu.org/cgit/grub.git/commit/?id=03f2515ae0c503406f1a99a2178405049c6555db]
+Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
+---
+ grub-core/net/net.c | 9 +++++++--
+ 1 file changed, 7 insertions(+), 2 deletions(-)
+
+diff --git a/grub-core/net/net.c b/grub-core/net/net.c
+index 38f19df..7c2cdf2 100644
+--- a/grub-core/net/net.c
++++ b/grub-core/net/net.c
+@@ -86,8 +86,13 @@ grub_net_link_layer_add_address (struct grub_net_card *card,
+ 
+   /* Add sender to cache table.  */
+   if (card->link_layer_table == NULL)
+-    card->link_layer_table = grub_zalloc (LINK_LAYER_CACHE_SIZE
+-					  * sizeof (card->link_layer_table[0]));
++    {
++      card->link_layer_table = grub_zalloc (LINK_LAYER_CACHE_SIZE
++					    * sizeof (card->link_layer_table[0]));
++      if (card->link_layer_table == NULL)
++	return;
++    }
++
+   entry = &(card->link_layer_table[card->new_ll_entry]);
+   entry->avail = 1;
+   grub_memcpy (&entry->ll_address, ll, sizeof (entry->ll_address));

meta/recipes-bsp/grub/grub2.inc

@@ -48,6 +48,7 @@ SRC_URI = "${GNU_MIRROR}/grub/grub-${PV}.tar.gz \
            file://CVE-2020-25632.patch \
            file://CVE-2020-25647.patch \
            file://0001-mmap-Fix-memory-leak-when-iterating-over-mapped-memo.patch \
+           file://0002-net-net-Fix-possible-dereference-to-of-a-NULL-pointe.patch \
            "
 SRC_URI[md5sum] = "5ce674ca6b2612d8939b9e6abed32934"
 SRC_URI[sha256sum] = "f10c85ae3e204dbaec39ae22fa3c5e99f0665417e91c2cb49b7e5031658ba6ea"