crypto: arm64/aes - fix handling sub-block CTS-CBC inputs

From: Eric Biggers <[email protected]>

In the new arm64 CTS-CBC implementation, return an error code rather than crashing on inputs shorter than AES_BLOCK_SIZE bytes. Also set cra_blocksize to AES_BLOCK_SIZE (like is done in the cts template) to indicate the minimum input size.

Fixes dd597fb33ff0 ("crypto: arm64/aes-blk - add support for CTS-CBC mode")

Signed-off-by Eric Biggers <[email protected]>

---
 arch/arm64/crypto/aes-glue.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

arch/arm64/crypto/aes-glue.c +9 -5

index 26d2b0263ba63..1e676625ef33f 100644
@@ -243,8 +243,11 @@ static int cts_cbc_encrypt(struct skcipher_request *req)
 
        skcipher_request_set_tfm(&rctx->subreq, tfm);
 
-       if (req->cryptlen == AES_BLOCK_SIZE)
+       if (req->cryptlen <= AES_BLOCK_SIZE) {
+               if (req->cryptlen < AES_BLOCK_SIZE)
+                       return -EINVAL;
                cbc_blocks = 1;
+       }
 
        if (cbc_blocks > 0) {
                unsigned int blocks;

@@ -305,8 +308,11 @@ static int cts_cbc_decrypt(struct skcipher_request *req)
 
        skcipher_request_set_tfm(&rctx->subreq, tfm);
 
-       if (req->cryptlen == AES_BLOCK_SIZE)
+       if (req->cryptlen <= AES_BLOCK_SIZE) {
+               if (req->cryptlen < AES_BLOCK_SIZE)
+                       return -EINVAL;
                cbc_blocks = 1;
+       }
 
        if (cbc_blocks > 0) {
                unsigned int blocks;

@@ -486,14 +492,13 @@ static struct skcipher_alg aes_algs[] = { {
                .cra_driver_name        = "__cts-cbc-aes-" MODE,
                .cra_priority           = PRIO,
                .cra_flags              = CRYPTO_ALG_INTERNAL,
-               .cra_blocksize          = 1,
+               .cra_blocksize          = AES_BLOCK_SIZE,
                .cra_ctxsize            = sizeof(struct crypto_aes_ctx),
                .cra_module             = THIS_MODULE,
        },
        .min_keysize    = AES_MIN_KEY_SIZE,
        .max_keysize    = AES_MAX_KEY_SIZE,
        .ivsize         = AES_BLOCK_SIZE,
-       .chunksize      = AES_BLOCK_SIZE,
        .walksize       = 2 * AES_BLOCK_SIZE,
        .setkey         = skcipher_aes_setkey,
        .encrypt        = cts_cbc_encrypt,
--

2.19.0

From: Eric Biggers <[email protected]>

In the new arm64 CTS-CBC implementation, return an error code rather than crashing on inputs shorter than AES_BLOCK_SIZE bytes. Also set cra_blocksize to AES_BLOCK_SIZE (like is done in the cts template) to indicate the minimum input size.

Fixes dd597fb33ff0 ("crypto: arm64/aes-blk - add support for CTS-CBC mode")

Signed-off-by Eric Biggers <[email protected]>