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| author | Kees Cook <keescook@chromium.org> | 2018-08-07 23:18:39 +0200 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2018-09-14 08:08:52 +0200 |
| commit | 6d39a1241ebc3bdd61d654c3058f0955c28c13fd (patch) | |
| tree | 96bb0af93ed1392637ac6dc974a55f36f0572d80 /drivers/md | |
| parent | crypto: arm/chacha20 - faster 8-bit rotations and other optimizations (diff) | |
| download | linux-6d39a1241ebc3bdd61d654c3058f0955c28c13fd.tar.xz linux-6d39a1241ebc3bdd61d654c3058f0955c28c13fd.zip | |
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@chromium.org>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/dm-integrity.c | 23 | ||||
| -rw-r--r-- | 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 378878599466..5c1197bc66f8 100644 --- a/drivers/md/dm-integrity.c +++ b/drivers/md/dm-integrity.c @@ -559,7 +559,12 @@ 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); @@ -1324,7 +1329,7 @@ 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; @@ -1333,8 +1338,14 @@ 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; @@ -1546,7 +1557,7 @@ retry_kmap: } 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))) { @@ -1596,7 +1607,7 @@ retry_kmap: 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 @@ -2023,7 +2034,7 @@ 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 |