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authorEric Biggers <ebiggers@google.com>2019-01-03 20:16:11 -0800
committerHerbert Xu <herbert@gondor.apana.org.au>2019-01-11 14:16:57 +0800
commit6c2e322b3621dc8be72e5c86d4fdb587434ba625 (patch)
treefaab76349687c512990fea9dfdd309b8a86bb918 /crypto/cfb.c
parent394a9e044702e6a8958a5e89d2a291605a587a2a (diff)
downloadlinux-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/cfb.c')
-rw-r--r--crypto/cfb.c8
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;
}