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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Mikulas Patocka <mpatocka@redhat.com>,
        Mike Snitzer <snitzer@redhat.com>
Subject: [PATCH 4.14 72/89] dm integrity: dont store cipher request on the stack
Date:   Mon, 22 Jan 2018 09:45:52 +0100
Message-Id: <20180122084001.630964161@linuxfoundation.org>
In-Reply-To: <20180122083954.683903493@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mikulas Patocka <mpatocka@redhat.com>

commit 717f4b1c52135f279112df82583e0c77e80f90de upstream.

Some asynchronous cipher implementations may use DMA.  The stack may
be mapped in the vmalloc area that doesn't support DMA.  Therefore,
the cipher request and initialization vector shouldn't be on the
stack.

Fix this by allocating the request and iv with kmalloc.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/md/dm-integrity.c |   49 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 37 insertions(+), 12 deletions(-)

--- a/drivers/md/dm-integrity.c
+++ b/drivers/md/dm-integrity.c
@@ -2558,7 +2558,8 @@ static int create_journal(struct dm_inte
 	int r = 0;
 	unsigned i;
 	__u64 journal_pages, journal_desc_size, journal_tree_size;
-	unsigned char *crypt_data = NULL;
+	unsigned char *crypt_data = NULL, *crypt_iv = NULL;
+	struct skcipher_request *req = NULL;
 
 	ic->commit_ids[0] = cpu_to_le64(0x1111111111111111ULL);
 	ic->commit_ids[1] = cpu_to_le64(0x2222222222222222ULL);
@@ -2616,9 +2617,20 @@ static int create_journal(struct dm_inte
 
 		if (blocksize == 1) {
 			struct scatterlist *sg;
-			SKCIPHER_REQUEST_ON_STACK(req, ic->journal_crypt);
-			unsigned char iv[ivsize];
-			skcipher_request_set_tfm(req, ic->journal_crypt);
+
+			req = skcipher_request_alloc(ic->journal_crypt, GFP_KERNEL);
+			if (!req) {
+				*error = "Could not allocate crypt request";
+				r = -ENOMEM;
+				goto bad;
+			}
+
+			crypt_iv = kmalloc(ivsize, GFP_KERNEL);
+			if (!crypt_iv) {
+				*error = "Could not allocate iv";
+				r = -ENOMEM;
+				goto bad;
+			}
 
 			ic->journal_xor = dm_integrity_alloc_page_list(ic);
 			if (!ic->journal_xor) {
@@ -2640,9 +2652,9 @@ static int create_journal(struct dm_inte
 				sg_set_buf(&sg[i], va, PAGE_SIZE);
 			}
 			sg_set_buf(&sg[i], &ic->commit_ids, sizeof ic->commit_ids);
-			memset(iv, 0x00, ivsize);
+			memset(crypt_iv, 0x00, ivsize);
 
-			skcipher_request_set_crypt(req, sg, sg, PAGE_SIZE * ic->journal_pages + sizeof ic->commit_ids, iv);
+			skcipher_request_set_crypt(req, sg, sg, PAGE_SIZE * ic->journal_pages + sizeof ic->commit_ids, crypt_iv);
 			init_completion(&comp.comp);
 			comp.in_flight = (atomic_t)ATOMIC_INIT(1);
 			if (do_crypt(true, req, &comp))
@@ -2658,10 +2670,22 @@ static int create_journal(struct dm_inte
 			crypto_free_skcipher(ic->journal_crypt);
 			ic->journal_crypt = NULL;
 		} else {
-			SKCIPHER_REQUEST_ON_STACK(req, ic->journal_crypt);
-			unsigned char iv[ivsize];
 			unsigned crypt_len = roundup(ivsize, blocksize);
 
+			req = skcipher_request_alloc(ic->journal_crypt, GFP_KERNEL);
+			if (!req) {
+				*error = "Could not allocate crypt request";
+				r = -ENOMEM;
+				goto bad;
+			}
+
+			crypt_iv = kmalloc(ivsize, GFP_KERNEL);
+			if (!crypt_iv) {
+				*error = "Could not allocate iv";
+				r = -ENOMEM;
+				goto bad;
+			}
+
 			crypt_data = kmalloc(crypt_len, GFP_KERNEL);
 			if (!crypt_data) {
 				*error = "Unable to allocate crypt data";
@@ -2669,8 +2693,6 @@ static int create_journal(struct dm_inte
 				goto bad;
 			}
 
-			skcipher_request_set_tfm(req, ic->journal_crypt);
-
 			ic->journal_scatterlist = dm_integrity_alloc_journal_scatterlist(ic, ic->journal);
 			if (!ic->journal_scatterlist) {
 				*error = "Unable to allocate sg list";
@@ -2694,12 +2716,12 @@ static int create_journal(struct dm_inte
 				struct skcipher_request *section_req;
 				__u32 section_le = cpu_to_le32(i);
 
-				memset(iv, 0x00, ivsize);
+				memset(crypt_iv, 0x00, ivsize);
 				memset(crypt_data, 0x00, crypt_len);
 				memcpy(crypt_data, &section_le, min((size_t)crypt_len, sizeof(section_le)));
 
 				sg_init_one(&sg, crypt_data, crypt_len);
-				skcipher_request_set_crypt(req, &sg, &sg, crypt_len, iv);
+				skcipher_request_set_crypt(req, &sg, &sg, crypt_len, crypt_iv);
 				init_completion(&comp.comp);
 				comp.in_flight = (atomic_t)ATOMIC_INIT(1);
 				if (do_crypt(true, req, &comp))
@@ -2757,6 +2779,9 @@ retest_commit_id:
 	}
 bad:
 	kfree(crypt_data);
+	kfree(crypt_iv);
+	skcipher_request_free(req);
+
 	return r;
 }