On Wed, 27 Dec 2017, Herbert Xu wrote:
> On Tue, Dec 26, 2017 at 02:21:53PM +0200, Gilad Ben-Yossef wrote:
> >
> > See how SKCIPHER_REQUEST_ON_STACK is being used with an asymmetric skcipher
> > in drivers/md/dm-integrity.c
>
> That's just broken. SKCIPHER_REQUEST_ON_STACK is only meant for
> sync algorithms and this code needs to be changed to either do the
> proper request allocation or switch over to allocating sync
> algorithms.
>
> Cheers,
Hi
Here I send a patch that moves those allocations to the heap.
Mikulas
From: Mikulas Patocka <mpato...@redhat.com>
Subject: [PATCH] dm-integrity: don't store cipher request on the stack
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.
This patch allocates the request and iv with kmalloc.
Signed-off-by: Mikulas Patocka <mpato...@redhat.com>
Cc: sta...@vger.kernel.org $ v4.12+
Index: linux-2.6/drivers/md/dm-integrity.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-integrity.c
+++ linux-2.6/drivers/md/dm-integrity.c
@@ -2559,7 +2559,8 @@ 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);
@@ -2617,9 +2618,20 @@ 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) {
@@ -2641,9 +2653,9 @@ 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))
@@ -2659,10 +2671,22 @@ 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";
@@ -2670,8 +2694,6 @@ 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";
@@ -2695,12 +2717,12 @@ 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, §ion_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 @@ retest_commit_id:
}
bad:
kfree(crypt_data);
+ kfree(crypt_iv);
+ skcipher_request_free(req);
+
return r;
}
