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dm: Remove VLA usage from hashes

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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>
This commit is contained in:
Kees Cook 2018-08-07 14:18:39 -07:00 committed by Herbert Xu
parent a1b22a5f45
commit 6d39a1241e
2 changed files with 21 additions and 7 deletions
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23
drivers/md/dm-integrity.c
View File

@ -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);

5
drivers/md/dm-verity-fec.c
View File

@ -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