3.16.70-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Eric Biggers <ebiggers@xxxxxxxxxx>
commit 251b7aea34ba3c4d4fdfa9447695642eb8b8b098 upstream.
The memcpy()s in the PCBC implementation use walk->iv as both the source
and destination, which has undefined behavior. These memcpy()'s are
actually unneeded, because walk->iv is already used to hold the previous
plaintext block XOR'd with the previous ciphertext block. Thus,
walk->iv is already updated to its final value.
So remove the broken and unnecessary memcpy()s.
Fixes: 91652be5d1b9 ("[CRYPTO] pcbc: Add Propagated CBC template")
Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
crypto/pcbc.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
--- a/crypto/pcbc.c
+++ b/crypto/pcbc.c
@@ -52,7 +52,7 @@ static int crypto_pcbc_encrypt_segment(s
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
- u8 *iv = walk->iv;
+ u8 * const iv = walk->iv;
do {
crypto_xor(iv, src, bsize);
@@ -76,7 +76,7 @@ static int crypto_pcbc_encrypt_inplace(s
int bsize = crypto_cipher_blocksize(tfm);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
- u8 *iv = walk->iv;
+ u8 * const iv = walk->iv;
u8 tmpbuf[bsize];
do {
@@ -89,8 +89,6 @@ static int crypto_pcbc_encrypt_inplace(s
src += bsize;
} while ((nbytes -= bsize) >= bsize);
- memcpy(walk->iv, iv, bsize);
-
return nbytes;
}
@@ -130,7 +128,7 @@ static int crypto_pcbc_decrypt_segment(s
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
- u8 *iv = walk->iv;
+ u8 * const iv = walk->iv;
do {
fn(crypto_cipher_tfm(tfm), dst, src);
@@ -142,8 +140,6 @@ static int crypto_pcbc_decrypt_segment(s
dst += bsize;
} while ((nbytes -= bsize) >= bsize);
- memcpy(walk->iv, iv, bsize);
-
return nbytes;
}
@@ -156,7 +152,7 @@ static int crypto_pcbc_decrypt_inplace(s
int bsize = crypto_cipher_blocksize(tfm);
unsigned int nbytes = walk->nbytes;
u8 *src = walk->src.virt.addr;
- u8 *iv = walk->iv;
+ u8 * const iv = walk->iv;
u8 tmpbuf[bsize];
do {
@@ -169,8 +165,6 @@ static int crypto_pcbc_decrypt_inplace(s
src += bsize;
} while ((nbytes -= bsize) >= bsize);
- memcpy(walk->iv, iv, bsize);
-
return nbytes;
}
