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author | Eric Biggers <ebiggers@google.com> | 2019-03-12 22:12:45 -0700 |
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committer | Herbert Xu <herbert@gondor.apana.org.au> | 2019-03-22 20:57:27 +0800 |
commit | 7aceaaef04eaaf6019ca159bc354d800559bba1d (patch) | |
tree | baa613e1d638ac59f2b40ee457a32e30fc643444 /crypto | |
parent | 62f95ae805fa9e1e84d47d3219adddd97b2654b7 (diff) | |
download | linux-7aceaaef04eaaf6019ca159bc354d800559bba1d.tar.gz linux-7aceaaef04eaaf6019ca159bc354d800559bba1d.tar.bz2 linux-7aceaaef04eaaf6019ca159bc354d800559bba1d.zip |
crypto: chacha-generic - fix use as arm64 no-NEON fallback
The arm64 implementations of ChaCha and XChaCha are failing the extra
crypto self-tests following my patches to test the !may_use_simd() code
paths, which previously were untested. The problem is as follows:
When !may_use_simd(), the arm64 NEON implementations fall back to the
generic implementation, which uses the skcipher_walk API to iterate
through the src/dst scatterlists. Due to how the skcipher_walk API
works, walk.stride is set from the skcipher_alg actually being used,
which in this case is the arm64 NEON algorithm. Thus walk.stride is
5*CHACHA_BLOCK_SIZE, not CHACHA_BLOCK_SIZE.
This unnecessarily large stride shouldn't cause an actual problem.
However, the generic implementation computes round_down(nbytes,
walk.stride). round_down() assumes the round amount is a power of 2,
which 5*CHACHA_BLOCK_SIZE is not, so it gives the wrong result.
This causes the following case in skcipher_walk_done() to be hit,
causing a WARN() and failing the encryption operation:
if (WARN_ON(err)) {
/* unexpected case; didn't process all bytes */
err = -EINVAL;
goto finish;
}
Fix it by rounding down to CHACHA_BLOCK_SIZE instead of walk.stride.
(Or we could replace round_down() with rounddown(), but that would add a
slow division operation every time, which I think we should avoid.)
Fixes: 2fe55987b262 ("crypto: arm64/chacha - use combined SIMD/ALU routine for more speed")
Cc: <stable@vger.kernel.org> # v5.0+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
-rw-r--r-- | crypto/chacha_generic.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/crypto/chacha_generic.c b/crypto/chacha_generic.c index 35b583101f4f..90ec0ec1b4f7 100644 --- a/crypto/chacha_generic.c +++ b/crypto/chacha_generic.c @@ -52,7 +52,7 @@ static int chacha_stream_xor(struct skcipher_request *req, unsigned int nbytes = walk.nbytes; if (nbytes < walk.total) - nbytes = round_down(nbytes, walk.stride); + nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE); chacha_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr, nbytes, ctx->nrounds); |