qemu: CVE-2018-7550

multiboot: bss_end_addr can be zero

The multiboot spec
(https://www.gnu.org/software/grub/manual/multiboot/),
section 3.1.3, allows for bss_end_addr to be zero.

A zero bss_end_addr signifies there is no .bss section.

Affects qemu < v2.12.0

(From OE-Core rev: 9f1d026168956e7bf45135577c123f7679a6ebba)

Signed-off-by: Jagadeesh Krishnanjanappa <jkrishnanjanappa@mvista.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 63 insertions, 0 deletions

diff --git a/meta/recipes-devtools/qemu/qemu/CVE-2018-7550.patch b/meta/recipes-devtools/qemu/qemu/CVE-2018-7550.patch
new file mode 100644
index 0000000000..9923d123a5
--- /dev/null
+++ b/meta/recipes-devtools/qemu/qemu/CVE-2018-7550.patch
@@ -0,0 +1,62 @@
+From 2a8fcd119eb7c6bb3837fc3669eb1b2dfb31daf8 Mon Sep 17 00:00:00 2001
+From: Jack Schwartz <jack.schwartz@oracle.com>
+Date: Thu, 21 Dec 2017 09:25:15 -0800
+Subject: [PATCH] multiboot: bss_end_addr can be zero
+
+The multiboot spec (https://www.gnu.org/software/grub/manual/multiboot/),
+section 3.1.3, allows for bss_end_addr to be zero.
+
+A zero bss_end_addr signifies there is no .bss section.
+
+CVE: CVE-2018-7550
+Upstream-Status: Backport [https://git.qemu.org/?p=qemu.git;a=commitdiff;h=2a8fcd119eb7c6bb3837fc3669eb1b2dfb31daf8]
+
+Suggested-by: Daniel Kiper <daniel.kiper@oracle.com>
+Signed-off-by: Jack Schwartz <jack.schwartz@oracle.com>
+Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
+Reviewed-by: Prasad J Pandit <pjp@fedoraproject.org>
+Signed-off-by: Kevin Wolf <kwolf@redhat.com>
+Signed-off-by: Jagadeesh Krishnanjanappa <jkrishnanjanappa@mvista.com>
+---
+ hw/i386/multiboot.c | 18 ++++++++++--------
+ 1 file changed, 10 insertions(+), 8 deletions(-)
+
+diff --git a/hw/i386/multiboot.c b/hw/i386/multiboot.c
+index 46d9c68bf5..bb8d8e4629 100644
+--- a/hw/i386/multiboot.c
++++ b/hw/i386/multiboot.c
+@@ -233,12 +233,6 @@ int load_multiboot(FWCfgState *fw_cfg,
+         mh_entry_addr = ldl_p(header+i+28);
+ 
+         if (mh_load_end_addr) {
+-            if (mh_bss_end_addr < mh_load_addr) {
+-                fprintf(stderr, "invalid mh_bss_end_addr address\n");
+-                exit(1);
+-            }
+-            mb_kernel_size = mh_bss_end_addr - mh_load_addr;
+-
+             if (mh_load_end_addr < mh_load_addr) {
+                 fprintf(stderr, "invalid mh_load_end_addr address\n");
+                 exit(1);
+@@ -249,8 +243,16 @@ int load_multiboot(FWCfgState *fw_cfg,
+                 fprintf(stderr, "invalid kernel_file_size\n");
+                 exit(1);
+             }
+-            mb_kernel_size = kernel_file_size - mb_kernel_text_offset;
+-            mb_load_size = mb_kernel_size;
++            mb_load_size = kernel_file_size - mb_kernel_text_offset;
++        }
++        if (mh_bss_end_addr) {
++            if (mh_bss_end_addr < (mh_load_addr + mb_load_size)) {
++                fprintf(stderr, "invalid mh_bss_end_addr address\n");
++                exit(1);
++            }
++            mb_kernel_size = mh_bss_end_addr - mh_load_addr;
++        } else {
++            mb_kernel_size = mb_load_size;
+         }
+ 
+         /* Valid if mh_flags sets MULTIBOOT_HEADER_HAS_VBE.
+-- 
+2.13.3
+
diff --git a/meta/recipes-devtools/qemu/qemu_2.11.1.bb b/meta/recipes-devtools/qemu/qemu_2.11.1.bb
index 7de21ac0fa..db7ead7682 100644
--- a/meta/recipes-devtools/qemu/qemu_2.11.1.bb
+++ b/meta/recipes-devtools/qemu/qemu_2.11.1.bb
@@ -24,6 +24,7 @@ SRC_URI = "http://wiki.qemu-project.org/download/${BP}.tar.bz2 \
            file://0012-arm-translate-a64-treat-DISAS_UPDATE-as-variant-of-D.patch \
            file://0013-ps2-check-PS2Queue-pointers-in-post_load-routine.patch \
            file://0001-CVE-2018-11806-QEMU-slirp-heap-buffer-overflow.patch \
+           file://CVE-2018-7550.patch \
            "
 UPSTREAM_CHECK_REGEX = "qemu-(?P<pver>\d+\..*)\.tar"