[patch 023/100] SCSI: sg: fix iovec bugs introduced by the block layer conversion

[Chris Wright]

-stable review patch.  If anyone has any objections, please let us know.
---------------------

From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>

upstream commit: 0fdf96b67ac2649cc1ddb29b316a0db11586c6a8

- needs to use copy_from_user for iovec before passing it to
blk_rq_map_user_iov().

- before the block layer conversion, if ->dxfer_len and sum of iovec
disagrees, the shorter one wins. However, currently sg returns
-EINVAL. This restores the old behavior.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
Acked-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxx
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
---
 drivers/scsi/sg.c |   28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1673,10 +1673,30 @@ static int sg_start_req(Sg_request *srp,
 		md->null_mapped = hp->dxferp ? 0 : 1;
 	}
 
-	if (iov_count)
-		res = blk_rq_map_user_iov(q, rq, md, hp->dxferp, iov_count,
-					  hp->dxfer_len, GFP_ATOMIC);
-	else
+	if (iov_count) {
+		int len, size = sizeof(struct sg_iovec) * iov_count;
+		struct iovec *iov;
+
+		iov = kmalloc(size, GFP_ATOMIC);
+		if (!iov)
+			return -ENOMEM;
+
+		if (copy_from_user(iov, hp->dxferp, size)) {
+			kfree(iov);
+			return -EFAULT;
+		}
+
+		len = iov_length(iov, iov_count);
+		if (hp->dxfer_len < len) {
+			iov_count = iov_shorten(iov, iov_count, hp->dxfer_len);
+			len = hp->dxfer_len;
+		}
+
+		res = blk_rq_map_user_iov(q, rq, md, (struct sg_iovec *)iov,
+					  iov_count,
+					  len, GFP_ATOMIC);
+		kfree(iov);
+	} else
 		res = blk_rq_map_user(q, rq, md, hp->dxferp,
 				      hp->dxfer_len, GFP_ATOMIC);
 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/