grub: fix incorrect use of a negative value

This patch adds a fix for an incorrect use of a negative value in grub's
util/glue-efi. 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: de1fe600212ff6d460bdc672d7ca0e13afbe7514)

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, 51 insertions, 0 deletions

diff --git a/meta/recipes-bsp/grub/files/0043-util-glue-efi-Fix-incorrect-use-of-a-possibly-negati.patch b/meta/recipes-bsp/grub/files/0043-util-glue-efi-Fix-incorrect-use-of-a-possibly-negati.patch
new file mode 100644
index 0000000000..66d7c0aa42
--- /dev/null
+++ b/meta/recipes-bsp/grub/files/0043-util-glue-efi-Fix-incorrect-use-of-a-possibly-negati.patch
@@ -0,0 +1,50 @@
+From e301a0f38a2130eb80f346c31e43bf5089af583c Mon Sep 17 00:00:00 2001
+From: Darren Kenny <darren.kenny@oracle.com>
+Date: Fri, 4 Dec 2020 15:04:28 +0000
+Subject: [PATCH] util/glue-efi: Fix incorrect use of a possibly negative value
+
+It is possible for the ftell() function to return a negative value,
+although it is fairly unlikely here, we should be checking for
+a negative value before we assign it to an unsigned value.
+
+Fixes: CID 73744
+
+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=1641d74e16f9d1ca35ba1a87ee4a0bf3afa48e72]
+Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
+---
+ util/glue-efi.c | 14 ++++++++++++--
+ 1 file changed, 12 insertions(+), 2 deletions(-)
+
+diff --git a/util/glue-efi.c b/util/glue-efi.c
+index 68f5316..de0fa6d 100644
+--- a/util/glue-efi.c
++++ b/util/glue-efi.c
+@@ -39,13 +39,23 @@ write_fat (FILE *in32, FILE *in64, FILE *out, const char *out_filename,
+   struct grub_macho_fat_header head;
+   struct grub_macho_fat_arch arch32, arch64;
+   grub_uint32_t size32, size64;
++  long size;
+   char *buf;
+ 
+   fseek (in32, 0, SEEK_END);
+-  size32 = ftell (in32);
++  size = ftell (in32);
++  if (size < 0)
++    grub_util_error ("cannot get end of input file '%s': %s",
++                    name32, strerror (errno));
++  size32 = (grub_uint32_t) size;
+   fseek (in32, 0, SEEK_SET);
++
+   fseek (in64, 0, SEEK_END);
+-  size64 = ftell (in64);
++  size = ftell (in64);
++  if (size < 0)
++    grub_util_error ("cannot get end of input file '%s': %s",
++                    name64, strerror (errno));
++  size64 = (grub_uint64_t) size;
+   fseek (in64, 0, SEEK_SET);
+ 
+   head.magic = grub_cpu_to_le32_compile_time (GRUB_MACHO_FAT_EFI_MAGIC);
diff --git a/meta/recipes-bsp/grub/grub2.inc b/meta/recipes-bsp/grub/grub2.inc
index a1fbc5e644..2f230065b2 100644
--- a/meta/recipes-bsp/grub/grub2.inc
+++ b/meta/recipes-bsp/grub/grub2.inc
@@ -89,6 +89,7 @@ SRC_URI = "${GNU_MIRROR}/grub/grub-${PV}.tar.gz \
            file://0040-loader-xnu-Check-if-pointer-is-NULL-before-using-it.patch \
            file://0041-util-grub-install-Fix-NULL-pointer-dereferences.patch \
            file://0042-util-grub-editenv-Fix-incorrect-casting-of-a-signed-.patch \
+           file://0043-util-glue-efi-Fix-incorrect-use-of-a-possibly-negati.patch \
            "
 SRC_URI[md5sum] = "5ce674ca6b2612d8939b9e6abed32934"
 SRC_URI[sha256sum] = "f10c85ae3e204dbaec39ae22fa3c5e99f0665417e91c2cb49b7e5031658ba6ea"