From 764b683a6180fd72c931c13fea98d383506a3475 Mon Sep 17 00:00:00 2001 From: Ben Cressey Date: Tue, 15 Sep 2026 00:37:35 +0000 Subject: [PATCH] dm-integrity: fix buffer overflow in inline mode with large tag size In inline mode, dm_integrity_check and dm_integrity_inline_recheck compute the checksum of each block into an on-stack buffer of HASH_MAX_DIGESTSIZE bytes. integrity_sector_checksum pads its result with zeroes up to the tag size, so if the tag size is larger than HASH_MAX_DIGESTSIZE, the padding runs past the end of the buffer. With CONFIG_STACKPROTECTOR the kernel panics in dm_integrity_check on the first read. Enlarge both buffers to hold MAX_TAG_SIZE bytes, as commit b93b6643e9b5 ("dm integrity: fix a crash with unusually large tag size") did for integrity_metadata. Note that this is not a security bug because the buffer overflow can only be triggered by root. Fixes: fb0987682c62 ("dm-integrity: introduce the Inline mode") Cc: stable@vger.kernel.org Signed-off-by: Ben Cressey Assisted-by: LLM Signed-off-by: Mikulas Patocka --- drivers/md/dm-integrity.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c index 92970e12267a..0862f31b8498 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -2721,7 +2721,7 @@ static void dm_integrity_inline_recheck(struct work_struct *w) outgoing_data = dio->integrity_payload + PAGE_SIZE; while (dio->bio_details.bi_iter.bi_size) { - char digest[HASH_MAX_DIGESTSIZE]; + char digest[MAX_T(size_t, HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)]; int r; struct bio_integrity_payload *bip; struct bio_vec bv; @@ -2788,7 +2788,7 @@ static inline bool dm_integrity_check(struct dm_integrity_c *ic, struct dm_integ unsigned pos = 0; while (dio->bio_details.bi_iter.bi_size) { - char digest[HASH_MAX_DIGESTSIZE]; + char digest[MAX_T(size_t, HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)]; struct bio_vec bv = bio_iter_iovec(bio, dio->bio_details.bi_iter); char *mem = integrity_kmap(ic, bv.bv_page); integrity_sector_checksum(ic, &dio->ahash_req, dio->bio_details.bi_iter.bi_sector, mem, bv.bv_offset, digest);