diff options
| author | Eric Biggers <ebiggers@google.com> | 2017-11-29 01:18:57 -0800 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2017-12-11 22:29:53 +1100 |
| commit | 2b4f27c36bcd46e820ddb9a8e6fe6a63fa4250b8 (patch) | |
| tree | f185bfdebe3769da7a82ea02cd394b3ed9736e91 | |
| parent | 50c4c4e268a2d7a3e58ebb698ac74da0de40ae36 (diff) | |
crypto: skcipher - set walk.iv for zero-length inputs
All the ChaCha20 algorithms as well as the ARM bit-sliced AES-XTS
algorithms call skcipher_walk_virt(), then access the IV (walk.iv)
before checking whether any bytes need to be processed (walk.nbytes).
But if the input is empty, then skcipher_walk_virt() doesn't set the IV,
and the algorithms crash trying to use the uninitialized IV pointer.
Fix it by setting the IV earlier in skcipher_walk_virt(). Also fix it
for the AEAD walk functions.
This isn't a perfect solution because we can't actually align the IV to
->cra_alignmask unless there are bytes to process, for one because the
temporary buffer for the aligned IV is freed by skcipher_walk_done(),
which is only called when there are bytes to process. Thus, algorithms
that require aligned IVs will still need to avoid accessing the IV when
walk.nbytes == 0. Still, many algorithms/architectures are fine with
IVs having any alignment, and even for those that aren't, a misaligned
pointer bug is much less severe than an uninitialized pointer bug.
This change also matches the behavior of the older blkcipher_walk API.
Fixes: 0cabf2af6f5a ("crypto: skcipher - Fix crash on zero-length input")
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: <stable@vger.kernel.org> # v4.14+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
| -rw-r--r-- | crypto/skcipher.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/crypto/skcipher.c b/crypto/skcipher.c index 778e0ff42bfa..11af5fd6a443 100644 --- a/crypto/skcipher.c +++ b/crypto/skcipher.c @@ -449,6 +449,8 @@ static int skcipher_walk_skcipher(struct skcipher_walk *walk, walk->total = req->cryptlen; walk->nbytes = 0; + walk->iv = req->iv; + walk->oiv = req->iv; if (unlikely(!walk->total)) return 0; @@ -456,9 +458,6 @@ static int skcipher_walk_skcipher(struct skcipher_walk *walk, scatterwalk_start(&walk->in, req->src); scatterwalk_start(&walk->out, req->dst); - walk->iv = req->iv; - walk->oiv = req->iv; - walk->flags &= ~SKCIPHER_WALK_SLEEP; walk->flags |= req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? SKCIPHER_WALK_SLEEP : 0; @@ -510,6 +509,8 @@ static int skcipher_walk_aead_common(struct skcipher_walk *walk, int err; walk->nbytes = 0; + walk->iv = req->iv; + walk->oiv = req->iv; if (unlikely(!walk->total)) return 0; @@ -525,9 +526,6 @@ static int skcipher_walk_aead_common(struct skcipher_walk *walk, scatterwalk_done(&walk->in, 0, walk->total); scatterwalk_done(&walk->out, 0, walk->total); - walk->iv = req->iv; - walk->oiv = req->iv; - if (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) walk->flags |= SKCIPHER_WALK_SLEEP; else |