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disk/lvm: Sanitize rlocn->offset to prevent wild read

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rlocn->offset is read directly from disk and added to the metadatabuf
pointer to create a pointer to a block of metadata. It's a 64-bit
quantity so as long as you don't overflow you can set subsequent
pointers to point anywhere in memory.

Require that rlocn->offset fits within the metadata buffer size.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Daniel Axtens 2021-01-22 14:43:58 +11:00 committed by Daniel Kiper
parent 1155d7dffd
commit 7012936847
1 changed files with 8 additions and 0 deletions
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8
grub-core/disk/lvm.c
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@ -248,6 +248,14 @@ grub_lvm_detect (grub_disk_t disk,
} }
rlocn = mdah->raw_locns; rlocn = mdah->raw_locns;
if (grub_le_to_cpu64 (rlocn->offset) >= grub_le_to_cpu64 (mda_size))
{
#ifdef GRUB_UTIL
grub_util_info ("metadata offset is beyond end of metadata area");
#endif
goto fail2;
}
if (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) > if (grub_le_to_cpu64 (rlocn->offset) + grub_le_to_cpu64 (rlocn->size) >
grub_le_to_cpu64 (mdah->size)) grub_le_to_cpu64 (mdah->size))
{ {