Patch "bio_copy_user_iov(): don't ignore ->iov_offset" has been added to the 4.9-stable tree

Patch "bio_copy_user_iov(): don't ignore ->iov_offset" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    bio_copy_user_iov(): don't ignore ->iov_offset

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bio_copy_user_iov-don-t-ignore-iov_offset.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 1cfd0ddd82232804e03f3023f6a58b50dfef0574 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun, 24 Sep 2017 10:21:15 -0400
Subject: bio_copy_user_iov(): don't ignore ->iov_offset

From: Al Viro <viro@zeniv.linux.org.uk>

commit 1cfd0ddd82232804e03f3023f6a58b50dfef0574 upstream.

Since "block: support large requests in blk_rq_map_user_iov" we
started to call it with partially drained iter; that works fine
on the write side, but reads create a copy of iter for completion
time.  And that needs to take the possibility of ->iov_iter != 0
into account...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 block/bio.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/block/bio.c
+++ b/block/bio.c
@@ -1171,8 +1171,8 @@ struct bio *bio_copy_user_iov(struct req
 	 */
 	bmd->is_our_pages = map_data ? 0 : 1;
 	memcpy(bmd->iov, iter->iov, sizeof(struct iovec) * iter->nr_segs);
-	iov_iter_init(&bmd->iter, iter->type, bmd->iov,
-			iter->nr_segs, iter->count);
+	bmd->iter = *iter;
+	bmd->iter.iov = bmd->iov;
 
 	ret = -ENOMEM;
 	bio = bio_kmalloc(gfp_mask, nr_pages);


Patches currently in stable-queue which might be from viro@zeniv.linux.org.uk are

queue-4.9/more-bio_map_user_iov-leak-fixes.patch
queue-4.9/direct-io-prevent-null-pointer-access-in-submit_page_section.patch
queue-4.9/bio_copy_user_iov-don-t-ignore-iov_offset.patch
queue-4.9/fix-unbalanced-page-refcounting-in-bio_map_user_iov.patch