Re: [patch NOT added to 3.12 stable tree] Don't feed anything but regular iovec's to blk_rq_map_user_iov

[Greg KH <greg@kroah.com>]

On Tue, Dec 13, 2016 at 03:40:53PM +0100, Jiri Slaby wrote:
> On 12/12/2016, 11:49 PM, Greg KH wrote:
> > On Mon, Dec 12, 2016 at 04:07:27PM +0100, Jiri Slaby wrote:
> >> From: Linus Torvalds <torvalds@linux-foundation.org>
> >>
> >> This patch does NOT apply to the 3.12 stable tree. If you still want
> >> it applied, please provide a backport.
> >>
> >> ===============
> >>
> >> commit a0ac402cfcdc904f9772e1762b3fda112dcc56a0 upstream.
> >>
> >> In theory we could map other things, but there's a reason that function
> >> is called "user_iov".  Using anything else (like splice can do) just
> >> confuses it.
> >>
> >> Reported-and-tested-by: Johannes Thumshirn <jthumshirn@suse.de>
> >> Cc: Al Viro <viro@ZenIV.linux.org.uk>
> >> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> >> ---
> >>  block/blk-map.c | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >> diff --git a/block/blk-map.c b/block/blk-map.c
> >> index b8657fa8dc9a..27fd8d92892d 100644
> >> --- a/block/blk-map.c
> >> +++ b/block/blk-map.c
> >> @@ -118,6 +118,9 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
> >>  	struct iov_iter i;
> >>  	int ret;
> >>  
> >> +	if (!iter_is_iovec(iter))
> >> +		goto fail;
> >> +
> >>  	if (map_data)
> >>  		copy = true;
> >>  	else if (iov_iter_alignment(iter) & align)
> >> @@ -140,6 +143,7 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
> >>  
> >>  unmap_rq:
> >>  	__blk_rq_unmap_user(bio);
> >> +fail:
> >>  	rq->bio = NULL;
> >>  	return -EINVAL;
> >>  }
> > 
> > I had to re-write this, feel free to steal the version I wrote for
> > 4.4.y, it's commit d41fb2fbb28d3a1085960edada6c046becd1fafd in the
> > linux-stable tree.
> 
> I tried, but unfortunately, 3.12 has no iter_is_iovec :(.

And you can't "open code" it for 3.12 by just checking the bitfields?  I
haven't looked at 3.12 in a long time and I know the iovec code has
changed a lot, sorry if this is a stupid question.

thanks,

greg k-h