crypto: skcipher - Copy iv from desc even for 0-len walks

commit 70d906bc17500edfa9bdd8c8b7e59618c7911613 upstream.

Some ciphers actually support encrypting zero length plaintexts. For
example, many AEAD modes support this. The resulting ciphertext for
those winds up being only the authentication tag, which is a result of
the key, the iv, the additional data, and the fact that the plaintext
had zero length. The blkcipher constructors won't copy the IV to the
right place, however, when using a zero length input, resulting in
some significant problems when ciphers call their initialization
routines, only to find that the ->iv parameter is uninitialized. One
such example of this would be using chacha20poly1305 with a zero length
input, which then calls chacha20, which calls the key setup routine,
which eventually OOPSes due to the uninitialized ->iv member.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>

diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
index 4a9c499ea78a4101a514310ced58aef056e069d7..1ef14284d09e56b57841bc6346ea858cfab89b60 100644 (file)
--- a/crypto/ablkcipher.c
+++ b/crypto/ablkcipher.c
@@ -280,12 +280,12 @@ static int ablkcipher_walk_first(struct ablkcipher_request *req,
        if (WARN_ON_ONCE(in_irq()))
                return -EDEADLK;
 
+       walk->iv = req->info;
        walk->nbytes = walk->total;
        if (unlikely(!walk->total))
                return 0;
 
        walk->iv_buffer = NULL;
-       walk->iv = req->info;
        if (unlikely(((unsigned long)walk->iv & alignmask))) {
                int err = ablkcipher_copy_iv(walk, tfm, alignmask);
                if (err)

diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c
index 0a1ebea3d6fc3b14305bfcf83c85122545b41f08..34e5d6507e545dfc8dfc2db49db1da613403e8e0 100644 (file)
--- a/crypto/blkcipher.c
+++ b/crypto/blkcipher.c
@@ -329,12 +329,12 @@ static int blkcipher_walk_first(struct blkcipher_desc *desc,
        if (WARN_ON_ONCE(in_irq()))
                return -EDEADLK;
 
+       walk->iv = desc->info;
        walk->nbytes = walk->total;
        if (unlikely(!walk->total))
                return 0;
 
        walk->buffer = NULL;
-       walk->iv = desc->info;
        if (unlikely(((unsigned long)walk->iv & alignmask))) {
                int err = blkcipher_copy_iv(walk, tfm, alignmask);
                if (err)