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dm integrity: fix memory corruption when tag_size is less than digest size

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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@vger.kernel.org # v4.19+
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mikulas Patocka 2022-04-03 14:38:22 -04:00 committed by Mike Snitzer
parent ce522ba9ef
commit 08c1af8f1c
1 changed files with 5 additions and 2 deletions
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7
drivers/md/dm-integrity.c
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@ -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;