Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751597AbcCDMhO (ORCPT ); Fri, 4 Mar 2016 07:37:14 -0500 Received: from mx2.suse.de ([195.135.220.15]:48992 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750817AbcCDMhL (ORCPT ); Fri, 4 Mar 2016 07:37:11 -0500 Date: Fri, 4 Mar 2016 13:37:29 +0100 From: Jan Kara To: Ricardo Ribalda Delgado Cc: albert@newtec.dk, Jan Kara , Pawel Osciak , Marek Szyprowski , Kyungmin Park , Hans Verkuil , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] [media] vb2-memops: Fix over allocation of frame vectors Message-ID: <20160304123729.GC17393@quack.suse.cz> References: <1457032369-10503-1-git-send-email-ricardo.ribalda@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1457032369-10503-1-git-send-email-ricardo.ribalda@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2595 Lines: 70 On Thu 03-03-16 20:12:48, Ricardo Ribalda Delgado wrote: > On page unaligned frames, create_framevec forces get_vaddr_frames to > allocate an extra page at the end of the buffer. Under some > circumstances, this leads to -EINVAL on VIDIOC_QBUF. > > E.g: > We have vm_a that vm_area that goes from 0x1000 to 0x3000. And a > frame that goes from 0x1800 to 0x2800, i.e. 2 pages. > > frame_vector_create will be called with the following params: > > get_vaddr_frames(0x1800 , 2, write, 1, vec); > > get_vaddr will allocate the first page after checking that the memory > 0x1800-0x27ff is valid, but it will not allocate the second page because > the range 0x2800-0x37ff is out of the vm_a range. This results in > create_framevec returning -EFAULT > > Error Trace: > [ 9083.793015] video0: VIDIOC_QBUF: 00:00:00.00000000 index=1, > type=vid-cap, flags=0x00002002, field=any, sequence=0, > memory=userptr, bytesused=0, offset/userptr=0x7ff2b023ca80, length=5765760 > [ 9083.793028] timecode=00:00:00 type=0, flags=0x00000000, > frames=0, userbits=0x00000000 > [ 9083.793117] video0: VIDIOC_QBUF: error -22: 00:00:00.00000000 > index=2, type=vid-cap, flags=0x00000000, field=any, sequence=0, > memory=userptr, bytesused=0, offset/userptr=0x7ff2b07bc500, length=5765760 > > Fixes: 21fb0cb7ec65 ("[media] vb2: Provide helpers for mapping virtual addresses") > Reported-by: Albert Antony > Signed-off-by: Ricardo Ribalda Delgado The patch looks good. Thanks for fixing this! You can add: Reviewed-by: Jan Kara Honza > --- > > Maybe we should cc stable. > > This error has not pop-out yet because userptr is usually called with memory > on the heap and malloc usually overallocate. This error has been a pain to trace :). > > Regards! > > > > drivers/media/v4l2-core/videobuf2-memops.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-memops.c b/drivers/media/v4l2-core/videobuf2-memops.c > index dbec5923fcf0..e4e4976c6849 100644 > --- a/drivers/media/v4l2-core/videobuf2-memops.c > +++ b/drivers/media/v4l2-core/videobuf2-memops.c > @@ -49,7 +49,7 @@ struct frame_vector *vb2_create_framevec(unsigned long start, > vec = frame_vector_create(nr); > if (!vec) > return ERR_PTR(-ENOMEM); > - ret = get_vaddr_frames(start, nr, write, 1, vec); > + ret = get_vaddr_frames(start & PAGE_MASK, nr, write, 1, vec); > if (ret < 0) > goto out_destroy; > /* We accept only complete set of PFNs */ > -- > 2.7.0 > -- Jan Kara SUSE Labs, CR