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grub: add a fix for a possible NULL pointer dereference

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This change fixes a possible NULL pointer dereference in grub's
EFI support. 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: a49ffdd81e020224ea3e94a266e49d40ebb7198a)

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>
This commit is contained in:
Marta Rybczynska
2022-02-18 11:05:15 +01:00
committed by Richard Purdie
parent 4a5a4dbcf6
commit c4ca12868c
2 changed files with 66 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
meta/recipes-bsp/grub/files/0007-kern-efi-mm-Fix-possible-NULL-pointer-dereference.patch
+65
View File
@@ -0,0 +1,65 @@
From be03a18b8767be50f16a845c389fd5ed29aae055 Mon Sep 17 00:00:00 2001
From: Darren Kenny <darren.kenny@oracle.com>
Date: Fri, 11 Dec 2020 15:03:13 +0000
Subject: [PATCH] kern/efi/mm: Fix possible NULL pointer dereference
The model of grub_efi_get_memory_map() is that if memory_map is NULL,
then the purpose is to discover how much memory should be allocated to
it for the subsequent call.
The problem here is that with grub_efi_is_finished set to 1, there is no
check at all that the function is being called with a non-NULL memory_map.
While this MAY be true, we shouldn't assume it.
The solution to this is to behave as expected, and if memory_map is NULL,
then don't try to use it and allow memory_map_size to be filled in, and
return 0 as is done later in the code if the buffer is too small (or NULL).
Additionally, drop unneeded ret = 1.
Fixes: CID 96632
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=6aee4bfd6973c714056fb7b56890b8d524e94ee1]
Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
---
grub-core/kern/efi/mm.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
diff --git a/grub-core/kern/efi/mm.c b/grub-core/kern/efi/mm.c
index b02fab1..5afcef7 100644
--- a/grub-core/kern/efi/mm.c
+++ b/grub-core/kern/efi/mm.c
@@ -328,15 +328,24 @@ grub_efi_get_memory_map (grub_efi_uintn_t *memory_map_size,
if (grub_efi_is_finished)
{
int ret = 1;
- if (*memory_map_size < finish_mmap_size)
+
+ if (memory_map != NULL)
{
- grub_memcpy (memory_map, finish_mmap_buf, *memory_map_size);
- ret = 0;
+ if (*memory_map_size < finish_mmap_size)
+ {
+ grub_memcpy (memory_map, finish_mmap_buf, *memory_map_size);
+ ret = 0;
+ }
+ else
+ grub_memcpy (memory_map, finish_mmap_buf, finish_mmap_size);
}
else
{
- grub_memcpy (memory_map, finish_mmap_buf, finish_mmap_size);
- ret = 1;
+ /*
+ * Incomplete, no buffer to copy into, same as
+ * GRUB_EFI_BUFFER_TOO_SMALL below.
+ */
+ ret = 0;
}
*memory_map_size = finish_mmap_size;
if (map_key)
meta/recipes-bsp/grub/grub2.inc
+1
View File
@@ -53,6 +53,7 @@ SRC_URI = "${GNU_MIRROR}/grub/grub-${PV}.tar.gz \
file://0004-kern-parser-Fix-resource-leak-if-argc-0.patch \
file://0005-efi-Fix-some-malformed-device-path-arithmetic-errors.patch \
file://0006-kern-efi-Fix-memory-leak-on-failure.patch \
file://0007-kern-efi-mm-Fix-possible-NULL-pointer-dereference.patch \
"
SRC_URI[md5sum] = "5ce674ca6b2612d8939b9e6abed32934"
SRC_URI[sha256sum] = "f10c85ae3e204dbaec39ae22fa3c5e99f0665417e91c2cb49b7e5031658ba6ea"