[PATCH 7/7] mv user buffer copy access_ok test to block helper

[michaelc@cs.wisc.edu]

From: Mike Christie <michaelc@cs.wisc.edu>

sg.c does a access_ok test on the user buffer when doing
indirect IO. bsg and scsi_ioctl.c did not, but it seems
like it would be ok to be common. This patch moves that
test to the block layer helpers.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
---
 block/ll_rw_blk.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 35b66ed..4327e23 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -2527,6 +2527,7 @@ static int copy_user_iov(struct bio *hea
 {
 	unsigned int iov_len = 0;
 	int ret, i = 0, iov_index = 0;
+	int read = bio_data_dir(head) == READ;
 	struct bio *bio;
 	struct bio_vec *bvec;
 	char __user *p = NULL;
@@ -2560,10 +2561,15 @@ continue_from_bvec:
 					 */
 					goto continue_from_bvec;
 				}
+
+				if (!access_ok(read ?
+					       VERIFY_WRITE : VERIFY_READ,
+					       p, iov_len))
+					return -EFAULT;
 			}
 
 			copy_bytes = min(iov_len, bvec->bv_len - bvec_offset);
-			if (bio_data_dir(head) == READ)
+			if (read)
 				ret = copy_to_user(p, addr, copy_bytes);
 			else
 				ret = copy_from_user(addr, p, copy_bytes);
-- 
1.4.1.1