Messages in this thread | | | Date | Tue, 13 Nov 2018 09:38:22 -0800 | From | Myungho Jung <> | Subject | Re: [PATCH] media: videobuf2-core: Fix error handling when fileio is deallocated |
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On Tue, Nov 13, 2018 at 12:56:18PM +0100, Hans Verkuil wrote: > On 11/13/18 11:27, Marek Szyprowski wrote: > > Hi Myungho, > > > > On 2018-11-12 01:49, Myungho Jung wrote: > >> The mutex that is held from vb2_fop_read() can be unlocked while waiting > >> for a buffer if the queue is streaming and blocking. Meanwhile, fileio > >> can be released. So, it should return an error if the fileio address is > >> changed. > >> > >> Signed-off-by: Myungho Jung <mhjungk@gmail.com> > >> Reported-by: syzbot+4180ff9ca6810b06c1e9@syzkaller.appspotmail.com > > > > Acked-by: Marek Szyprowski <m.szyprowski@samsung.com> > > Sorry: > > Nacked-by: Hans Verkuil <hans.verkuil@cisco.com> > > This addresses the symptom, not the underlying cause. > > I have a patch that fixes the actual cause that I plan to post soon > after I review it a bit more. > > Regards, > > Hans >
Hi Hans,
Thanks for explaining the root cause. I was also thinking a similar patch with your second one. It looks like the reported syzbot is needed to be added to your first patch.
Regards, Myungho
> > > > Thanks for analyzing the code and fixing this issue! > > > >> --- > >> drivers/media/common/videobuf2/videobuf2-core.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c > >> index 975ff5669f72..bff94752eb27 100644 > >> --- a/drivers/media/common/videobuf2/videobuf2-core.c > >> +++ b/drivers/media/common/videobuf2/videobuf2-core.c > >> @@ -2564,6 +2564,10 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_ > >> dprintk(5, "vb2_dqbuf result: %d\n", ret); > >> if (ret) > >> return ret; > >> + if (fileio != q->fileio) { > >> + dprintk(3, "fileio deallocated\n"); > >> + return -EFAULT; > >> + } > >> fileio->dq_count += 1; > >> > >> fileio->cur_index = index; > > > > Best regards > > >
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