dm integrity: fix a crash with unusually large tag size

commit b93b6643e9b5a7f260b931e97f56ffa3fa65e26d upstream.

If the user specifies tag size larger than HASH_MAX_DIGESTSIZE,
there's a crash in integrity_metadata().

Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 145bc2e..5624877 100644 (file)
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -1514,7 +1514,7 @@ static void integrity_metadata(struct work_struct *w)
                struct bio *bio = dm_bio_from_per_bio_data(dio, sizeof(struct dm_integrity_io));
                char *checksums;
                unsigned extra_space = unlikely(digest_size > ic->tag_size) ? digest_size - ic->tag_size : 0;
-               char checksums_onstack[HASH_MAX_DIGESTSIZE];
+               char checksums_onstack[max((size_t)HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
                unsigned sectors_to_process = dio->range.n_sectors;
                sector_t sector = dio->range.logical_sector;
 
@@ -1743,7 +1743,7 @@ retry_kmap:
                                } while (++s < ic->sectors_per_block);
 #ifdef INTERNAL_VERIFY
                                if (ic->internal_hash) {
-                                       char checksums_onstack[max(HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
+                                       char checksums_onstack[max((size_t)HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
 
                                        integrity_sector_checksum(ic, logical_sector, mem + bv.bv_offset, checksums_onstack);
                                        if (unlikely(memcmp(checksums_onstack, journal_entry_tag(ic, je), ic->tag_size))) {