Merge tag 'dm-3.17-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fix from Mike Snitzer:
 "Fix a 3.17-rc1 regression introduced by switching the DM crypt target
  to using per-bio data"

* tag 'dm-3.17-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm crypt: fix access beyond the end of allocated space

1 files changed, 19 insertions, 6 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 2785007e0e46..cd15e0801228 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1688,6 +1688,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         unsigned int key_size, opt_params;
         unsigned long long tmpll;
         int ret;
+        size_t iv_size_padding;
         struct dm_arg_set as;
         const char *opt_string;
         char dummy;
@@ -1724,20 +1725,32 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
         cc->dmreq_start = sizeof(struct ablkcipher_request);
         cc->dmreq_start += crypto_ablkcipher_reqsize(any_tfm(cc));
-        cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment());
-        cc->dmreq_start += crypto_ablkcipher_alignmask(any_tfm(cc)) &
-                           ~(crypto_tfm_ctx_alignment() - 1);
+        cc->dmreq_start = ALIGN(cc->dmreq_start, __alignof__(struct dm_crypt_request));
+
+        if (crypto_ablkcipher_alignmask(any_tfm(cc)) < CRYPTO_MINALIGN) {
+                /* Allocate the padding exactly */
+                iv_size_padding = -(cc->dmreq_start + sizeof(struct dm_crypt_request))
+                                & crypto_ablkcipher_alignmask(any_tfm(cc));
+        } else {
+                /*
+                 * If the cipher requires greater alignment than kmalloc
+                 * alignment, we don't know the exact position of the
+                 * initialization vector. We must assume worst case.
+                 */
+                iv_size_padding = crypto_ablkcipher_alignmask(any_tfm(cc));
+        }
 
         cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
-                        sizeof(struct dm_crypt_request) + cc->iv_size);
+                        sizeof(struct dm_crypt_request) + iv_size_padding + cc->iv_size);
         if (!cc->req_pool) {
                 ti->error = "Cannot allocate crypt request mempool";
                 goto bad;
         }
 
         cc->per_bio_data_size = ti->per_bio_data_size =
-                                sizeof(struct dm_crypt_io) + cc->dmreq_start +
-                                sizeof(struct dm_crypt_request) + cc->iv_size;
+                ALIGN(sizeof(struct dm_crypt_io) + cc->dmreq_start +
+                      sizeof(struct dm_crypt_request) + iv_size_padding + cc->iv_size,
+                      ARCH_KMALLOC_MINALIGN);
 
         cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
         if (!cc->page_pool) {