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

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commit 08c1af8f1c13bbf210f1760132f4df24d0ed46d6 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mikulas Patocka 2022-04-03 14:38:22 -04:00 committed by Greg Kroah-Hartman
parent 8eb78da898
commit 6a95d91c0b
1 changed files with 5 additions and 2 deletions
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7
drivers/md/dm-integrity.c
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@ -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;