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- 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
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