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From: Kees Cook <keescook@chromium.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>,
	Eric Biggers <ebiggers@google.com>,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	Alasdair Kergon <agk@redhat.com>, Rabin Vincent <rabinv@axis.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Pavel Machek <pavel@ucw.cz>, Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Philipp Reisner <philipp.reisner@linbit.com>,
	Lars Ellenberg <lars.ellenberg@linbit.com>,
	Jens Axboe <axboe@kernel.dk>,
	Giovanni Cabiddu <giovanni.cabiddu@intel.com>,
	Mike Snitzer <snitzer@redhat.com>,
	Paul Mackerras <paulus@samba.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	David Howells <dhowells@redhat.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	Tudor-Dan Ambarus <tudor.ambarus@microchip.com>,
	Jia-Ju Bai <baijiaju1990@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	David Woodhouse <dwmw@amazon.co.uk>,
	Will Deacon <will.deacon@arm.com>,
	dm-devel@redhat.com, linux-pm@vger.kernel.org,
	linux-crypto@vger.kernel.org, drbd-dev@lists.linbit.com,
	linux-block@vger.kernel.org, qat-linux@intel.com,
	linux-ppp@vger.kernel.org, netdev@vger.kernel.org,
	devel@driverdev.osuosl.org, linux-afs@lists.infradead.org,
	linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v6 04/18] dm: Remove VLA usage from hashes
Date: Tue, 24 Jul 2018 16:49:22 +0000	[thread overview]
Message-ID: <20180724164936.37477-5-keescook@chromium.org> (raw)
In-Reply-To: <20180724164936.37477-1-keescook@chromium.org>

In the quest to remove all stack VLA usage from the kernel[1], this uses
the new HASH_MAX_DIGESTSIZE from the crypto layer to allocate the upper
bounds on stack usage.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/md/dm-integrity.c  | 23 +++++++++++++++++------
 drivers/md/dm-verity-fec.c |  5 ++++-
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
index 86438b2f10dd..884edd7cf1d0 100644
--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -521,7 +521,12 @@ static void section_mac(struct dm_integrity_c *ic, unsigned section, __u8 result
 		}
 		memset(result + size, 0, JOURNAL_MAC_SIZE - size);
 	} else {
-		__u8 digest[size];
+		__u8 digest[HASH_MAX_DIGESTSIZE];
+
+		if (WARN_ON(size > sizeof(digest))) {
+			dm_integrity_io_error(ic, "digest_size", -EINVAL);
+			goto err;
+		}
 		r = crypto_shash_final(desc, digest);
 		if (unlikely(r)) {
 			dm_integrity_io_error(ic, "crypto_shash_final", r);
@@ -1244,7 +1249,7 @@ 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[ic->tag_size + extra_space];
+		char checksums_onstack[HASH_MAX_DIGESTSIZE];
 		unsigned sectors_to_process = dio->range.n_sectors;
 		sector_t sector = dio->range.logical_sector;
 
@@ -1253,8 +1258,14 @@ static void integrity_metadata(struct work_struct *w)
 
 		checksums = kmalloc((PAGE_SIZE >> SECTOR_SHIFT >> ic->sb->log2_sectors_per_block) * ic->tag_size + extra_space,
 				    GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN);
-		if (!checksums)
+		if (!checksums) {
 			checksums = checksums_onstack;
+			if (WARN_ON(extra_space &&
+				    digest_size > sizeof(checksums_onstack))) {
+				r = -EINVAL;
+				goto error;
+			}
+		}
 
 		__bio_for_each_segment(bv, bio, iter, dio->orig_bi_iter) {
 			unsigned pos;
@@ -1466,7 +1477,7 @@ static bool __journal_read_write(struct dm_integrity_io *dio, struct bio *bio,
 				} while (++s < ic->sectors_per_block);
 #ifdef INTERNAL_VERIFY
 				if (ic->internal_hash) {
-					char checksums_onstack[max(crypto_shash_digestsize(ic->internal_hash), ic->tag_size)];
+					char checksums_onstack[max(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))) {
@@ -1516,7 +1527,7 @@ static bool __journal_read_write(struct dm_integrity_io *dio, struct bio *bio,
 				if (ic->internal_hash) {
 					unsigned digest_size = crypto_shash_digestsize(ic->internal_hash);
 					if (unlikely(digest_size > ic->tag_size)) {
-						char checksums_onstack[digest_size];
+						char checksums_onstack[HASH_MAX_DIGESTSIZE];
 						integrity_sector_checksum(ic, logical_sector, (char *)js, checksums_onstack);
 						memcpy(journal_entry_tag(ic, je), checksums_onstack, ic->tag_size);
 					} else
@@ -1937,7 +1948,7 @@ static void do_journal_write(struct dm_integrity_c *ic, unsigned write_start,
 				    unlikely(from_replay) &&
 #endif
 				    ic->internal_hash) {
-					char test_tag[max(crypto_shash_digestsize(ic->internal_hash), ic->tag_size)];
+					char test_tag[max_t(size_t, HASH_MAX_DIGESTSIZE, MAX_TAG_SIZE)];
 
 					integrity_sector_checksum(ic, sec + ((l - j) << ic->sb->log2_sectors_per_block),
 								  (char *)access_journal_data(ic, i, l), test_tag);
diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c
index 684af08d0747..0ce04e5b4afb 100644
--- a/drivers/md/dm-verity-fec.c
+++ b/drivers/md/dm-verity-fec.c
@@ -212,12 +212,15 @@ static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io,
 	struct dm_verity_fec_io *fio = fec_io(io);
 	u64 block, ileaved;
 	u8 *bbuf, *rs_block;
-	u8 want_digest[v->digest_size];
+	u8 want_digest[HASH_MAX_DIGESTSIZE];
 	unsigned n, k;
 
 	if (neras)
 		*neras = 0;
 
+	if (WARN_ON(v->digest_size > sizeof(want_digest)))
+		return -EINVAL;
+
 	/*
 	 * read each of the rsn data blocks that are part of the RS block, and
 	 * interleave contents to available bufs
-- 
2.17.1


  parent reply	other threads:[~2018-07-24 16:49 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-24 16:49 [PATCH v6 00/18] crypto: Remove VLA usage Kees Cook
2018-07-24 16:49 ` [PATCH v6 01/18] crypto: xcbc: " Kees Cook
2018-07-24 16:49 ` [PATCH v6 02/18] crypto: cbc: " Kees Cook
2018-07-24 16:49 ` [PATCH v6 03/18] crypto: hash: " Kees Cook
2018-07-24 16:49 ` Kees Cook [this message]
2018-07-24 16:49 ` [PATCH v6 05/18] crypto alg: Introduce generic max blocksize and alignmask Kees Cook
2018-07-24 16:49 ` [PATCH v6 06/18] crypto: qat: Remove VLA usage Kees Cook
2018-07-24 16:49 ` [PATCH v6 07/18] crypto: shash: Remove VLA usage in unaligned hashing Kees Cook
2018-07-24 16:49 ` [PATCH v6 08/18] crypto: skcipher: Remove VLA usage for SKCIPHER_REQUEST_ON_STACK Kees Cook
2018-07-24 16:49 ` [PATCH v6 09/18] ppp: mppe: Remove VLA usage Kees Cook
2018-07-24 16:49 ` [PATCH v6 10/18] x86/power/64: " Kees Cook
2018-07-25 11:32   ` Rafael J. Wysocki
2018-07-25 18:01     ` Kees Cook
2018-08-06 10:28       ` Rafael J. Wysocki
2018-07-24 16:49 ` [PATCH v6 11/18] dm crypt: Convert essiv from ahash to shash Kees Cook
2018-07-24 16:49 ` [PATCH v6 12/18] drbd: Convert " Kees Cook
2018-07-24 16:49 ` [PATCH v6 13/18] wireless/lib80211: " Kees Cook
2018-07-25  7:24   ` Johannes Berg
2018-07-24 16:49 ` [PATCH v6 14/18] staging: rtl8192u: ieee80211: " Kees Cook
2018-07-24 16:49 ` [PATCH v6 15/18] staging: rtl8192e: " Kees Cook
2018-07-24 16:49 ` [PATCH v6 16/18] rxrpc: Reuse SKCIPHER_REQUEST_ON_STACK buffer Kees Cook
2018-07-24 16:49 ` [PATCH v6 17/18] crypto: ccm: Remove VLA usage Kees Cook
2018-07-24 16:57   ` Ard Biesheuvel
2018-07-24 17:51     ` Kees Cook
2018-07-24 16:49 ` [PATCH v6 18/18] crypto: Remove AHASH_REQUEST_ON_STACK Kees Cook
2018-07-24 17:31   ` Joe Perches
2018-07-24 17:53     ` Kees Cook

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