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.
This patch fixes the corruption.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.19+
---
drivers/md/dm-integrity.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
Index: linux-2.6/drivers/md/dm-integrity.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-integrity.c 2022-04-02 14:17:13.000000000 +0200
+++ linux-2.6/drivers/md/dm-integrity.c 2022-04-02 14:43:06.000000000 +0200
@@ -4399,6 +4399,7 @@ try_smaller_buffer:
}
if (ic->internal_hash) {
+ size_t recalc_tags_size;
ic->recalc_wq = alloc_workqueue("dm-integrity-recalc", WQ_MEM_RECLAIM, 1);
if (!ic->recalc_wq ) {
ti->error = "Cannot allocate workqueue";
@@ -4412,8 +4413,10 @@ 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;
--
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