[PATCH v2 00/11] crypto: Remove VLA usage

Kees Cook
2018-06-25T21:13:20Z

Hi,

v2:
- use 512 instead of PAGE_SIZE / 8 to avoid bloat on large-page archs.
- swtich xcbc to "16" max universally.
- fix typo in bounds check for dm buffer size.
- examine actual reqsizes for skcipher and ahash instead of guessing.
- improve names and comments for alg maxes

This is nearly the last of the VLA removals[1], but it's one of the
largest because crypto gets used in lots of places. After looking
through code, usage, reading the threads Gustavo started, and comparing
the use-cases to the other VLA removals that have landed in the kernel,
I think this series is likely the best way forward to shut the door on
VLAs forever.

As background, the crypto stack usage is for callers to do an immediate
bit of work that doesn't allocate new memory. This means that other VLA
removal techniques (like just using kmalloc) aren't workable, and the
next common technique is needed: examination of maximum stack usage and
the addition of sanity checks. This series does that, and in several
cases, these maximums were already implicit in the code.

This series is intended to land via the crypto tree, though it touches
dm as well, since there are dependent patches (new crypto #defines
being used).

Thanks!

-Kees

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

Kees Cook (11):
crypto: xcbc: Remove VLA usage
crypto: cbc: Remove VLA usage
crypto: shash: Remove VLA usage
dm integrity: Remove VLA usage
crypto: ahash: Remove VLA usage
dm verity fec: Remove VLA usage
crypto alg: Introduce generic max blocksize and alignmask
crypto: qat: Remove VLA usage
crypto: shash: Remove VLA usage in unaligned hashing
crypto: ahash: Remove VLA usage for AHASH_REQUEST_ON_STACK
crypto: skcipher: Remove VLA usage for SKCIPHER_REQUEST_ON_STACK

crypto/ahash.c | 4 ++--
crypto/algapi.c | 7 ++++++-
crypto/algif_hash.c | 2 +-
crypto/shash.c | 25 +++++++++++-------------
crypto/xcbc.c | 9 +++++++--
drivers/crypto/qat/qat_common/qat_algs.c | 8 ++++++--
drivers/md/dm-integrity.c | 23 ++++++++++++++++------
drivers/md/dm-verity-fec.c | 5 ++++-
include/crypto/algapi.h | 4 +++-
include/crypto/cbc.h | 4 +++-
include/crypto/hash.h | 12 ++++++++++--
include/crypto/internal/hash.h | 1 +
include/crypto/internal/skcipher.h | 1 +
include/crypto/skcipher.h | 4 +++-
include/linux/compiler-gcc.h | 1 -
15 files changed, 75 insertions(+), 35 deletions(-)

--
2.17.1