Patch "crypto: virtio: Fix src/dst scatterlist calculation in __virtio_crypto_skcipher_do_req()" has been added to the 5.6-stable tree

This is a note to let you know that I've just added the patch titled

crypto: virtio: Fix src/dst scatterlist calculation in __virtio_crypto_skcipher_do_req()

to the 5.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
crypto-virtio-fix-src-dst-scatterlist-calculation-in-__virtio_crypto_skcipher_do_req.patch
and it can be found in the queue-5.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From b02989f37fc5e865ceeee9070907e4493b3a21e2 Mon Sep 17 00:00:00 2001
From: "Longpeng(Mike)" <[email protected]>
Date: Tue, 2 Jun 2020 15:04:59 +0800
Subject: crypto: virtio: Fix src/dst scatterlist calculation in __virtio_crypto_skcipher_do_req()

From: Longpeng(Mike) <[email protected]>

commit b02989f37fc5e865ceeee9070907e4493b3a21e2 upstream.

The system will crash when the users insmod crypto/tcrypt.ko with mode=38 ( testing "cts(cbc(aes))" ).

Usually the next entry of one sg will be @sg@ + 1, but if this sg element is part of a chained scatterlist, it could jump to the start of a new scatterlist array. Fix it by sg_next() on calculation of src/dst scatterlist.

---
 drivers/crypto/virtio/virtio_crypto_algs.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

@@ -350,13 +350,18 @@ __virtio_crypto_skcipher_do_req(struct v
 	int err;
 	unsigned long flags;
 	struct scatterlist outhdr, iv_sg, status_sg, **sgs;
-	int i;
 	u64 dst_len;
 	unsigned int num_out = 0, num_in = 0;
 	int sg_total;
 	uint8_t *iv;
+	struct scatterlist *sg;
 
 	src_nents = sg_nents_for_len(req->src, req->cryptlen);
+	if (src_nents < 0) {
+		pr_err("Invalid number of src SG.\n");
+		return src_nents;
+	}
+
 	dst_nents = sg_nents(req->dst);
 
 	pr_debug("virtio_crypto: Number of sgs (src_nents: %d, dst_nents: %d)\n",

@@ -443,12 +448,12 @@ __virtio_crypto_skcipher_do_req(struct v
 	vc_sym_req->iv = iv;
 
 	/* Source data */
-	for (i = 0; i < src_nents; i++)
-		sgs[num_out++] = &req->src[i];
+	for (sg = req->src; src_nents; sg = sg_next(sg), src_nents--)
+		sgs[num_out++] = sg;
 
 	/* Destination data */
-	for (i = 0; i < dst_nents; i++)
-		sgs[num_out + num_in++] = &req->dst[i];
+	for (sg = req->dst; sg; sg = sg_next(sg))
+		sgs[num_out + num_in++] = sg;
 
 	/* Status */
 	sg_init_one(&status_sg, &vc_req->status, sizeof(vc_req->status));

Patches currently in stable-queue which might be from [email protected] are

queue-5.6/crypto-virtio-fix-src-dst-scatterlist-calculation-in-__virtio_crypto_skcipher_do_req.patch queue-5.6/crypto-virtio-fix-dest-length-calculation-in-__virtio_crypto_skcipher_do_req.patch queue-5.6/crypto-virtio-fix-use-after-free-in-virtio_crypto_skcipher_finalize_req.patch