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

Chris Wright
2009-04-23T07:33:48Z

[-- Attachment #1: scsi-sg-fix-iovec-bugs-introduced-by-the-block-layer-conversion.patch --]
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-stable review patch. If anyone has any objections, please let us know.
---------------------

From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

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@lab.ntt.co.jp>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
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);