| 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 |
| |