Hi
Here I'm sending a backport of the patch
08c1af8f1c13bbf210f1760132f4df24d0ed46d6 for the kernel 4.19.
Mikulas
On Mon, 18 Apr 2022, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> The patch below does not apply to the 4.19-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
It is possible to set up dm-integrity in such a way that the
"tag_size" parameter is less than the actual digest size. In this
situation, a part of the digest beyond tag_size is ignored.
In this case, dm-integrity would write beyond the end of the
ic->recalc_tags array and corrupt memory. The corruption happened in
integrity_recalc->integrity_sector_checksum->crypto_shash_final.
Fix this corruption by increasing the tags array so that it has enough
padding at the end to accomodate the loop in integrity_recalc() being
able to write a full digest size for the last member of the tags
array.
Cc: stable@xxxxxxxxxxxxxxx # v4.19+
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
drivers/md/dm-integrity.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
Index: linux-stable/drivers/md/dm-integrity.c
===================================================================
--- linux-stable.orig/drivers/md/dm-integrity.c 2022-04-19 10:52:45.000000000 +0200
+++ linux-stable/drivers/md/dm-integrity.c 2022-04-19 10:54:41.000000000 +0200
@@ -3504,6 +3504,7 @@ try_smaller_buffer:
}
if (ic->sb->flags & cpu_to_le32(SB_FLAG_RECALCULATING)) {
+ size_t recalc_tags_size;
if (!ic->internal_hash) {
r = -EINVAL;
ti->error = "Recalculate is only valid with internal hash";
@@ -3522,8 +3523,10 @@ try_smaller_buffer:
r = -ENOMEM;
goto bad;
}
- ic->recalc_tags = kvmalloc_array(RECALC_SECTORS >> ic->sb->log2_sectors_per_block,
- ic->tag_size, GFP_KERNEL);
+ recalc_tags_size = (RECALC_SECTORS >> ic->sb->log2_sectors_per_block) * ic->tag_size;
+ if (crypto_shash_digestsize(ic->internal_hash) > ic->tag_size)
+ recalc_tags_size += crypto_shash_digestsize(ic->internal_hash) - ic->tag_size;
+ ic->recalc_tags = kvmalloc(recalc_tags_size, GFP_KERNEL);
if (!ic->recalc_tags) {
ti->error = "Cannot allocate tags for recalculating";
r = -ENOMEM;
