grub: add a fix for a possible NULL dereference

This patch adds a fix for a possible NULL dereference in grub's
libgcrypt/mpi. 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: 33aa1a133cf2893a6d3a1f94bd098ee1c16a8abc)

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>

2 files changed, 34 insertions, 0 deletions

diff --git a/meta/recipes-bsp/grub/files/0027-libgcrypt-mpi-Fix-possible-NULL-dereference.patch b/meta/recipes-bsp/grub/files/0027-libgcrypt-mpi-Fix-possible-NULL-dereference.patch
new file mode 100644
index 0000000000..08299d021e
--- /dev/null
+++ b/meta/recipes-bsp/grub/files/0027-libgcrypt-mpi-Fix-possible-NULL-dereference.patch
@@ -0,0 +1,33 @@
+From d26c8771293637b0465f2cb67d97cb58bacc62da Mon Sep 17 00:00:00 2001
+From: Darren Kenny <darren.kenny@oracle.com>
+Date: Thu, 26 Nov 2020 10:41:54 +0000
+Subject: [PATCH] libgcrypt/mpi: Fix possible NULL dereference
+
+The code in gcry_mpi_scan() assumes that buffer is not NULL, but there
+is no explicit check for that, so we add one.
+
+Fixes: CID 73757
+
+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=ae0f3fabeba7b393113d5dc185b6aff9b728136d]
+Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
+---
+ grub-core/lib/libgcrypt/mpi/mpicoder.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/grub-core/lib/libgcrypt/mpi/mpicoder.c b/grub-core/lib/libgcrypt/mpi/mpicoder.c
+index 7ecad27..6fe3891 100644
+--- a/grub-core/lib/libgcrypt/mpi/mpicoder.c
++++ b/grub-core/lib/libgcrypt/mpi/mpicoder.c
+@@ -379,6 +379,9 @@ gcry_mpi_scan (struct gcry_mpi **ret_mpi, enum gcry_mpi_format format,
+   unsigned int len;
+   int secure = (buffer && gcry_is_secure (buffer));
+ 
++  if (!buffer)
++    return gcry_error (GPG_ERR_INV_ARG);
++
+   if (format == GCRYMPI_FMT_SSH)
+     len = 0;
+   else
diff --git a/meta/recipes-bsp/grub/grub2.inc b/meta/recipes-bsp/grub/grub2.inc
index be35ac04ef..ef409bdd6a 100644
--- a/meta/recipes-bsp/grub/grub2.inc
+++ b/meta/recipes-bsp/grub/grub2.inc
@@ -73,6 +73,7 @@ SRC_URI = "${GNU_MIRROR}/grub/grub-${PV}.tar.gz \
            file://0024-zfsinfo-Correct-a-check-for-error-allocating-memory.patch \
            file://0025-affs-Fix-memory-leaks.patch \
            file://0026-libgcrypt-mpi-Fix-possible-unintended-sign-extension.patch \
+           file://0027-libgcrypt-mpi-Fix-possible-NULL-dereference.patch \
            "
 SRC_URI[md5sum] = "5ce674ca6b2612d8939b9e6abed32934"
 SRC_URI[sha256sum] = "f10c85ae3e204dbaec39ae22fa3c5e99f0665417e91c2cb49b7e5031658ba6ea"