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authorEric Biggers <ebiggers@google.com>2019-03-12 22:12:45 -0700
committerHerbert Xu <herbert@gondor.apana.org.au>2019-03-22 20:57:27 +0800
commit7aceaaef04eaaf6019ca159bc354d800559bba1d (patch)
treebaa613e1d638ac59f2b40ee457a32e30fc643444 /crypto
parent62f95ae805fa9e1e84d47d3219adddd97b2654b7 (diff)
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.c2
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);