dm integrity: don't store cipher request on the stack

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.

Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-integrity.c

@@ -2559,7 +2559,8 @@ static int create_journal(struct dm_integrity_c *ic, char **error)
 	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);
@@ -2617,9 +2618,20 @@ static int create_journal(struct dm_integrity_c *ic, char **error)
 
 		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) {
@@ -2641,9 +2653,9 @@ static int create_journal(struct dm_integrity_c *ic, char **error)
 				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))
@@ -2659,10 +2671,22 @@ static int create_journal(struct dm_integrity_c *ic, char **error)
 			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";
@@ -2670,8 +2694,6 @@ static int create_journal(struct dm_integrity_c *ic, char **error)
 				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";
@@ -2695,12 +2717,12 @@ static int create_journal(struct dm_integrity_c *ic, char **error)
 				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))
@@ -2758,6 +2780,9 @@ static int create_journal(struct dm_integrity_c *ic, char **error)
 	}
 bad:
 	kfree(crypt_data);
+	kfree(crypt_iv);
+	skcipher_request_free(req);
+
 	return r;
 }