dm verity: fix crash on bufio buffer that was allocated with vmalloc

Since commit d1ac3ff008fb ("dm verity: switch to using asynchronous hash
crypto API") dm-verity uses asynchronous crypto calls for verification,
so that it can use hardware with asynchronous processing of crypto
operations.

These asynchronous calls don't support vmalloc memory, but the buffer data
can be allocated with vmalloc if dm-bufio is short of memory and uses a
reserved buffer that was preallocated in dm_bufio_client_create().

Fix verity_hash_update() so that it deals with vmalloc'd memory
correctly.

Reported-by: "Xiao, Jin" <jin.xiao@intel.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Fixes: d1ac3ff008fb ("dm verity: switch to using asynchronous hash crypto API")
Cc: stable@vger.kernel.org # 4.12+
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index 12decdbd722d866ed48a0a6a8d8b8f2e0a6aefbc..fc65f0dedf7f702b31d6adf21b8a2b26238c8b43 100644 (file)
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -99,10 +99,26 @@ static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
 {
        struct scatterlist sg;
 
-       sg_init_one(&sg, data, len);
-       ahash_request_set_crypt(req, &sg, NULL, len);
-
-       return crypto_wait_req(crypto_ahash_update(req), wait);
+       if (likely(!is_vmalloc_addr(data))) {
+               sg_init_one(&sg, data, len);
+               ahash_request_set_crypt(req, &sg, NULL, len);
+               return crypto_wait_req(crypto_ahash_update(req), wait);
+       } else {
+               do {
+                       int r;
+                       size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
+                       flush_kernel_vmap_range((void *)data, this_step);
+                       sg_init_table(&sg, 1);
+                       sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
+                       ahash_request_set_crypt(req, &sg, NULL, this_step);
+                       r = crypto_wait_req(crypto_ahash_update(req), wait);
+                       if (unlikely(r))
+                               return r;
+                       data += this_step;
+                       len -= this_step;
+               } while (len);
+               return 0;
+       }
 }
 
 /*