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| author | Eric Biggers <ebiggers@google.com> | 2019-01-03 20:16:11 -0800 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2019-01-11 14:16:57 +0800 |
| commit | 6c2e322b3621dc8be72e5c86d4fdb587434ba625 (patch) | |
| tree | faab76349687c512990fea9dfdd309b8a86bb918 /crypto | |
| parent | 394a9e044702e6a8958a5e89d2a291605a587a2a (diff) | |
| download | linux-6c2e322b3621dc8be72e5c86d4fdb587434ba625.tar.bz2 | |
crypto: cfb - remove bogus memcpy() with src == dest
The memcpy() in crypto_cfb_decrypt_inplace() uses walk->iv as both the
source and destination, which has undefined behavior. It is unneeded
because walk->iv is already used to hold the previous ciphertext block;
thus, walk->iv is already updated to its final value. So, remove it.
Also, note that in-place decryption is the only case where the previous
ciphertext block is not directly available. Therefore, as a related
cleanup I also updated crypto_cfb_encrypt_segment() to directly use the
previous ciphertext block rather than save it into walk->iv. This makes
it consistent with in-place encryption and out-of-place decryption; now
only in-place decryption is different, because it has to be.
Fixes: a7d85e06ed80 ("crypto: cfb - add support for Cipher FeedBack mode")
Cc: <stable@vger.kernel.org> # v4.17+
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/cfb.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/crypto/cfb.c b/crypto/cfb.c index 183e8a9c3312..4abfe32ff845 100644 --- a/crypto/cfb.c +++ b/crypto/cfb.c @@ -77,12 +77,14 @@ static int crypto_cfb_encrypt_segment(struct skcipher_walk *walk, do { crypto_cfb_encrypt_one(tfm, iv, dst); crypto_xor(dst, src, bsize); - memcpy(iv, dst, bsize); + iv = dst; src += bsize; dst += bsize; } while ((nbytes -= bsize) >= bsize); + memcpy(walk->iv, iv, bsize); + return nbytes; } @@ -162,7 +164,7 @@ static int crypto_cfb_decrypt_inplace(struct skcipher_walk *walk, const unsigned int bsize = crypto_cfb_bsize(tfm); unsigned int nbytes = walk->nbytes; u8 *src = walk->src.virt.addr; - u8 *iv = walk->iv; + u8 * const iv = walk->iv; u8 tmp[MAX_CIPHER_BLOCKSIZE]; do { @@ -172,8 +174,6 @@ static int crypto_cfb_decrypt_inplace(struct skcipher_walk *walk, src += bsize; } while ((nbytes -= bsize) >= bsize); - memcpy(walk->iv, iv, bsize); - return nbytes; } |