grub2/SOURCES/0453-disk-lvm-Don-t-go-beyond-the-end-of-the-data-we-read.patch

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2021-03-02 18:56:20 +00:00
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Thu, 21 Jan 2021 17:59:14 +1100
Subject: [PATCH] disk/lvm: Don't go beyond the end of the data we read from
disk
We unconditionally trusted offset_xl from the LVM label header, even if
it told us that the PV header/disk locations were way off past the end
of the data we read from disk.
Require that the offset be sane, fixing an OOB read and crash.
Fixes: CID 314367, CID 314371
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/disk/lvm.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/grub-core/disk/lvm.c b/grub-core/disk/lvm.c
2022-05-10 07:20:45 +00:00
index 4fbb3eac0..0f466040a 100644
2021-03-02 18:56:20 +00:00
--- a/grub-core/disk/lvm.c
+++ b/grub-core/disk/lvm.c
@@ -142,6 +142,20 @@ grub_lvm_detect (grub_disk_t disk,
goto fail;
}
+ /*
+ * We read a grub_lvm_pv_header and then 2 grub_lvm_disk_locns that
+ * immediately follow the PV header. Make sure we have space for both.
+ */
+ if (grub_le_to_cpu32 (lh->offset_xl) >=
+ GRUB_LVM_LABEL_SIZE - sizeof (struct grub_lvm_pv_header) -
+ 2 * sizeof (struct grub_lvm_disk_locn))
+ {
+#ifdef GRUB_UTIL
+ grub_util_info ("LVM PV header/disk locations are beyond the end of the block");
+#endif
+ goto fail;
+ }
+
pvh = (struct grub_lvm_pv_header *) (buf + grub_le_to_cpu32(lh->offset_xl));
for (i = 0, j = 0; i < GRUB_LVM_ID_LEN; i++)