FAILED: patch "[PATCH] crypto: virtio: Fix dest length calculation in" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d90ca42012db2863a9a30b564a2ace6016594bda Mon Sep 17 00:00:00 2001
From: "Longpeng(Mike)" <[email protected]>
Date: Tue, 2 Jun 2020 15:05:01 +0800
Subject: [PATCH] crypto: virtio: Fix dest length calculation in
__virtio_crypto_skcipher_do_req()

The src/dst length is not aligned with AES_BLOCK_SIZE(which is 16) in some testcases in tcrypto.ko.

For example, the src/dst length of one of cts(cbc(aes))'s testcase is 17, the crypto_virtio driver will set @src_data_len=16 but @dst_data_len=17 in this case and get a wrong at then end.

SRC: pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp (17 bytes)
EXP: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc pp (17 bytes)
DST: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 00 (pollute the last bytes) (pp: plaintext cc:ciphertext)

Fix this issue by limit the length of dest buffer.

index 52261b6c247e..cb8a6ea2a4bc 100644
@@ -407,6 +407,7 @@ __virtio_crypto_skcipher_do_req(struct virtio_crypto_sym_request *vc_sym_req,
 		goto free;
 	}
 
+	dst_len = min_t(unsigned int, req->cryptlen, dst_len);
 	pr_debug("virtio_crypto: src_len: %u, dst_len: %llu\n",
 			req->cryptlen, dst_len);