| From 7ca60898ccb2e1dc5e47dca5d53eb42922a0a0bc Mon Sep 17 00:00:00 2001 |
| From: Kevin Wolf <kwolf@redhat.com> |
| Date: Thu, 26 Jul 2018 16:24:47 +0200 |
| Subject: [PATCH 5/8] multiboot: Reject kernels exceeding the address space |
| |
| RH-Author: Kevin Wolf <kwolf@redhat.com> |
| Message-id: <20180726162448.22072-6-kwolf@redhat.com> |
| Patchwork-id: 81514 |
| O-Subject: [RHEL-7.6/7.5.z qemu-kvm PATCH 5/6] multiboot: Reject kernels exceeding the address space |
| Bugzilla: 1549822 |
| RH-Acked-by: John Snow <jsnow@redhat.com> |
| RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com> |
| RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com> |
| |
| The code path where mh_load_end_addr is non-zero in the Multiboot |
| header checks that mh_load_end_addr >= mh_load_addr and so |
| mb_load_size is checked. However, mb_load_size is not checked when |
| calculated from the file size, when mh_load_end_addr is 0. |
| |
| If the kernel binary size is larger than can fit in the address space |
| after load_addr, we ended up with a kernel_size that is smaller than |
| load_size, which means that we read the file into a too small buffer. |
| |
| Add a check to reject kernel files with such Multiboot headers. |
| |
| Signed-off-by: Kevin Wolf <kwolf@redhat.com> |
| Reviewed-by: Jack Schwartz <jack.schwartz@oracle.com> |
| (cherry picked from commit b17a9054a0652a1481be48a6729e972abf02412f) |
| Signed-off-by: Kevin Wolf <kwolf@redhat.com> |
| Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com> |
| |
| hw/i386/multiboot.c | 4 ++++ |
| 1 file changed, 4 insertions(+) |
| |
| diff --git a/hw/i386/multiboot.c b/hw/i386/multiboot.c |
| index 56889e8..6f489a5 100644 |
| |
| |
| @@ -226,6 +226,10 @@ int load_multiboot(FWCfgState *fw_cfg, |
| } |
| mb_load_size = kernel_file_size - mb_kernel_text_offset; |
| } |
| + if (mb_load_size > UINT32_MAX - mh_load_addr) { |
| + error_report("kernel does not fit in address space"); |
| + exit(1); |
| + } |
| if (mh_bss_end_addr) { |
| if (mh_bss_end_addr < (mh_load_addr + mb_load_size)) { |
| error_report("invalid bss_end_addr address"); |
| -- |
| 1.8.3.1 |
| |