grub: avoid a memory leak

This patch fixes a memory leak in grub's loader/xnu when an error is
detected in grub_xnu_writetree_toheap(). It is a part of a security
series [1].

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

Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

2 files changed, 78 insertions, 0 deletions

diff --git a/meta/recipes-bsp/grub/files/0039-loader-xnu-Free-driverkey-data-when-an-error-is-dete.patch b/meta/recipes-bsp/grub/files/0039-loader-xnu-Free-driverkey-data-when-an-error-is-dete.patch
new file mode 100644
index 0000000000..f9ad0fc34c
--- /dev/null
+++ b/meta/recipes-bsp/grub/files/0039-loader-xnu-Free-driverkey-data-when-an-error-is-dete.patch
@@ -0,0 +1,77 @@
+From 81117a77a9e945ee5e7c1f12bd5667e2a16cbe32 Mon Sep 17 00:00:00 2001
+From: Marco A Benatto <mbenatto@redhat.com>
+Date: Mon, 30 Nov 2020 12:18:24 -0300
+Subject: [PATCH] loader/xnu: Free driverkey data when an error is detected in
+ grub_xnu_writetree_toheap()
+
+... to avoid memory leaks.
+
+Fixes: CID 96640
+
+Signed-off-by: Marco A Benatto <mbenatto@redhat.com>
+Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
+
+Upstream-Status: Backport [https://git.savannah.gnu.org/cgit/grub.git/commit/?id=4b4027b6b1c877d7ab467896b04c7bd1aadcfa15]
+Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>
+---
+ grub-core/loader/xnu.c | 24 ++++++++++++++++++++----
+ 1 file changed, 20 insertions(+), 4 deletions(-)
+
+diff --git a/grub-core/loader/xnu.c b/grub-core/loader/xnu.c
+index b3029a8..39ceff8 100644
+--- a/grub-core/loader/xnu.c
++++ b/grub-core/loader/xnu.c
+@@ -224,26 +224,33 @@ grub_xnu_writetree_toheap (grub_addr_t *target, grub_size_t *size)
+   if (! memorymap)
+     return grub_errno;
+ 
+-  driverkey = (struct grub_xnu_devtree_key *) grub_malloc (sizeof (*driverkey));
++  driverkey = (struct grub_xnu_devtree_key *) grub_zalloc (sizeof (*driverkey));
+   if (! driverkey)
+     return grub_errno;
+   driverkey->name = grub_strdup ("DeviceTree");
+   if (! driverkey->name)
+-    return grub_errno;
++    {
++      err = grub_errno;
++      goto fail;
++    }
++
+   driverkey->datasize = sizeof (*extdesc);
+   driverkey->next = memorymap->first_child;
+   memorymap->first_child = driverkey;
+   driverkey->data = extdesc
+     = (struct grub_xnu_extdesc *) grub_malloc (sizeof (*extdesc));
+   if (! driverkey->data)
+-    return grub_errno;
++    {
++      err = grub_errno;
++      goto fail;
++    }
+ 
+   /* Allocate the space based on the size with dummy value. */
+   *size = grub_xnu_writetree_get_size (grub_xnu_devtree_root, "/");
+   err = grub_xnu_heap_malloc (ALIGN_UP (*size + 1, GRUB_XNU_PAGESIZE),
+ 			      &src, target);
+   if (err)
+-    return err;
++    goto fail;
+ 
+   /* Put real data in the dummy. */
+   extdesc->addr = *target;
+@@ -252,6 +259,15 @@ grub_xnu_writetree_toheap (grub_addr_t *target, grub_size_t *size)
+   /* Write the tree to heap. */
+   grub_xnu_writetree_toheap_real (src, grub_xnu_devtree_root, "/");
+   return GRUB_ERR_NONE;
++
++ fail:
++  memorymap->first_child = NULL;
++
++  grub_free (driverkey->data);
++  grub_free (driverkey->name);
++  grub_free (driverkey);
++
++  return err;
+ }
+ 
+ /* Find a key or value in parent key. */
diff --git a/meta/recipes-bsp/grub/grub2.inc b/meta/recipes-bsp/grub/grub2.inc
index c9e7a06a3f..eebe9a7233 100644
--- a/meta/recipes-bsp/grub/grub2.inc
+++ b/meta/recipes-bsp/grub/grub2.inc
@@ -85,6 +85,7 @@ SRC_URI = "${GNU_MIRROR}/grub/grub-${PV}.tar.gz \
            file://0036-gfxmenu-gui_list-Remove-code-that-coverity-is-flaggi.patch \
            file://0037-loader-bsd-Check-for-NULL-arg-up-front.patch \
            file://0038-loader-xnu-Fix-memory-leak.patch \
+           file://0039-loader-xnu-Free-driverkey-data-when-an-error-is-dete.patch \
            "
 SRC_URI[md5sum] = "5ce674ca6b2612d8939b9e6abed32934"
 SRC_URI[sha256sum] = "f10c85ae3e204dbaec39ae22fa3c5e99f0665417e91c2cb49b7e5031658ba6ea"