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crypto: chacha20 - fix handling of chunked input 

Commit 9ae433bc79 ("crypto: chacha20 - convert generic and x86 versions
to skcipher") ported the existing chacha20 code to use the new skcipher
API, and introduced a bug along the way. Unfortunately, the tcrypt tests
did not catch the error, and it was only found recently by Tobias.

Stefan kindly diagnosed the error, and proposed a fix which is similar
to the one below, with the exception that 'walk.stride' is used rather
than the hardcoded block size. This does not actually matter in this
case, but it's a better example of how to use the skcipher walk API.

Fixes: 9ae433bc79 ("crypto: chacha20 - convert generic and x86 ...")
Cc: <stable@vger.kernel.org> # v4.11+
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Reported-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
zero-colors
Ard Biesheuvel 2017-08-14 14:28:14 +01:00 committed by Herbert Xu
parent dea3eb8b45
commit 4de437265e
1 changed files with 7 additions and 2 deletions
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9
crypto/chacha20_generic.c
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@ -91,9 +91,14 @@ int crypto_chacha20_crypt(struct skcipher_request *req)
crypto_chacha20_init(state, ctx, walk.iv);
while (walk.nbytes > 0) {
unsigned int nbytes = walk.nbytes;
if (nbytes < walk.total)
nbytes = round_down(nbytes, walk.stride);
chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
walk.nbytes);
err = skcipher_walk_done(&walk, 0);
nbytes);
err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
}
return err;