block: fix SG_IO to return a proper error value

blk_rq_unmap_user() returns -EFAULT if a program passes an invalid
address to kernel. SG_IO path needs to pass the returned value to user
space instead of ignoring it.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index 626ee274c5c4..84b7f8709f41 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -217,7 +217,7 @@ static int blk_fill_sghdr_rq(struct request_queue *q, struct request *rq,
 static int blk_complete_sghdr_rq(struct request *rq, struct sg_io_hdr *hdr,
                                  struct bio *bio)
 {
-        int ret = 0;
+        int r, ret = 0;
 
         /*
          * fill in all the output members
@@ -242,7 +242,9 @@ static int blk_complete_sghdr_rq(struct request *rq, struct sg_io_hdr *hdr,
                         ret = -EFAULT;
         }
 
-        blk_rq_unmap_user(bio);
+        r = blk_rq_unmap_user(bio);
+        if (!ret)
+                ret = r;
         blk_put_request(rq);
 
         return ret;