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Message-Id: <20180724164936.37477-5-keescook@chromium.org>
Date: Tue, 24 Jul 2018 09:49:22 -0700
From: Kees Cook <keescook@...omium.org>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Kees Cook <keescook@...omium.org>, Arnd Bergmann <arnd@...db.de>,
Eric Biggers <ebiggers@...gle.com>,
"Gustavo A. R. Silva" <gustavo@...eddedor.com>,
Alasdair Kergon <agk@...hat.com>,
Rabin Vincent <rabinv@...s.com>,
Tim Chen <tim.c.chen@...ux.intel.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Pavel Machek <pavel@....cz>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Philipp Reisner <philipp.reisner@...bit.com>,
Lars Ellenberg <lars.ellenberg@...bit.com>,
Jens Axboe <axboe@...nel.dk>,
Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
Mike Snitzer <snitzer@...hat.com>,
Paul Mackerras <paulus@...ba.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
David Howells <dhowells@...hat.com>,
Johannes Berg <johannes@...solutions.net>,
Tudor-Dan Ambarus <tudor.ambarus@...rochip.com>,
Jia-Ju Bai <baijiaju1990@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
David Woodhouse <dwmw@...zon.co.uk>,
Will Deacon <will.deacon@....com>, dm-devel@...hat.com,
linux-pm@...r.kernel.org, linux-crypto@...r.kernel.org,
drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
qat-linux@...el.com, linux-ppp@...r.kernel.org,
netdev@...r.kernel.org, devel@...verdev.osuosl.org,
linux-afs@...ts.infradead.org, linux-wireless@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v6 04/18] dm: Remove VLA usage from hashes
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@...omium.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
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