| From 27a79bf38e6d050e497eb96a3fdddce43af25577 Mon Sep 17 00:00:00 2001 |
| From: Daniel Axtens <dja@axtens.net> |
| Date: Thu, 21 Jan 2021 18:19:51 +1100 |
| Subject: [PATCH] disk/lvm: Don't blast past the end of the circular metadata |
| buffer |
| |
| This catches at least some OOB reads, and it's possible I suppose that |
| if 2 * mda_size is less than GRUB_LVM_MDA_HEADER_SIZE it might catch some |
| OOB writes too (although that hasn't showed up as a crash in fuzzing yet). |
| |
| It's a bit ugly and I'd appreciate better suggestions. |
| |
| Signed-off-by: Daniel Axtens <dja@axtens.net> |
| Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> |
| Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com> |
| --- |
| grub-core/disk/lvm.c | 10 ++++++++++ |
| 1 file changed, 10 insertions(+) |
| |
| diff --git a/grub-core/disk/lvm.c b/grub-core/disk/lvm.c |
| index 8136122..36da575 100644 |
| --- a/grub-core/disk/lvm.c |
| +++ b/grub-core/disk/lvm.c |
| @@ -214,6 +214,16 @@ grub_lvm_detect (grub_disk_t disk, |
| if (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) > |
| grub_le_to_cpu64 (mdah->size)) |
| { |
| + if (2 * mda_size < GRUB_LVM_MDA_HEADER_SIZE || |
| + (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) - |
| + grub_le_to_cpu64 (mdah->size) > mda_size - GRUB_LVM_MDA_HEADER_SIZE)) |
| + { |
| +#ifdef GRUB_UTIL |
| + grub_util_info ("cannot copy metadata wrap in circular buffer"); |
| +#endif |
| + goto fail2; |
| + } |
| + |
| /* Metadata is circular. Copy the wrap in place. */ |
| grub_memcpy (metadatabuf + mda_size, |
| metadatabuf + GRUB_LVM_MDA_HEADER_SIZE, |
| -- |
| 2.14.2 |
| |