| Message ID | 1349880405-26049-23-git-send-email-t.stanislaws@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Tomasz, Thanks for the patch. On Wednesday 10 October 2012 16:46:41 Tomasz Stanislawski wrote: > From: Marek Szyprowski <m.szyprowski@samsung.com> > > The DMA transfer must be aligned to a specific value. If userptr is not > aligned to DMA requirements then unexpected corruptions of the memory may > occur before or after a buffer. To prevent such situations, all unligned > userptr buffers are rejected at VIDIOC_QBUF. > > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > Acked-by: Hans Verkuil <hans.verkuil@cisco.com> > --- > drivers/media/v4l2-core/videobuf2-dma-contig.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c > b/drivers/media/v4l2-core/videobuf2-dma-contig.c index 2d661fd..571a919 > 100644 > --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c > +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c > @@ -493,6 +493,18 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, > unsigned long vaddr, struct vm_area_struct *vma; > struct sg_table *sgt; > unsigned long contig_size; > + unsigned long dma_align = dma_get_cache_alignment(); > + > + /* Only cache aligned DMA transfers are reliable */ > + if (!IS_ALIGNED(vaddr | size, dma_align)) { > + pr_debug("user data must be aligned to %lu bytes\n", dma_align); > + return ERR_PTR(-EINVAL); > + } Looks good to me. > + if (!size) { > + pr_debug("size is zero\n"); > + return ERR_PTR(-EINVAL); > + } Can this happen ? The vb2 core already has /* Check if the provided plane buffer is large enough */ if (planes[plane].length < q->plane_sizes[plane]) { ret = -EINVAL; goto err; } Unless queue_setup sets plane_sizes to 0 we can't reach vb2_dc_get_userptr. > buf = kzalloc(sizeof *buf, GFP_KERNEL); > if (!buf)
Hi Laurent, Thank you for the review. Please refer to the comments below. On 10/11/2012 11:36 PM, Laurent Pinchart wrote: > Hi Tomasz, > > Thanks for the patch. > > On Wednesday 10 October 2012 16:46:41 Tomasz Stanislawski wrote: >> From: Marek Szyprowski <m.szyprowski@samsung.com> >> >> The DMA transfer must be aligned to a specific value. If userptr is not >> aligned to DMA requirements then unexpected corruptions of the memory may >> occur before or after a buffer. To prevent such situations, all unligned >> userptr buffers are rejected at VIDIOC_QBUF. >> >> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> >> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> >> --- >> drivers/media/v4l2-core/videobuf2-dma-contig.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c >> b/drivers/media/v4l2-core/videobuf2-dma-contig.c index 2d661fd..571a919 >> 100644 >> --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c >> +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c >> @@ -493,6 +493,18 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, >> unsigned long vaddr, struct vm_area_struct *vma; >> struct sg_table *sgt; >> unsigned long contig_size; >> + unsigned long dma_align = dma_get_cache_alignment(); >> + >> + /* Only cache aligned DMA transfers are reliable */ >> + if (!IS_ALIGNED(vaddr | size, dma_align)) { >> + pr_debug("user data must be aligned to %lu bytes\n", dma_align); >> + return ERR_PTR(-EINVAL); >> + } > > Looks good to me. > >> + if (!size) { >> + pr_debug("size is zero\n"); >> + return ERR_PTR(-EINVAL); >> + } > > Can this happen ? The vb2 core already has > > /* Check if the provided plane buffer is large enough */ > if (planes[plane].length < q->plane_sizes[plane]) { > ret = -EINVAL; > goto err; > } > > Unless queue_setup sets plane_sizes to 0 we can't reach vb2_dc_get_userptr. > Yes.. unfortunately, some drivers set plane_size to 0 at queue_setup. Especially, if REQBUFS is called before any S_FMT. Maybe it is just a driver bug. However, VB2 makes no sanity check if plane_sizes[] is zero. I was not able to find in Documentation nor code comments any explicit statement that plane_size cannot be zero. Therefore I have to reject reject a 0-bytes-long user pointer at vb2_dc_get_userptr before creating an empty scatterlist and passing it to the DMA layer. Regards, Tomasz Stanislawski >> buf = kzalloc(sizeof *buf, GFP_KERNEL); >> if (!buf) >
On Fri 12 October 2012 09:44:05 Tomasz Stanislawski wrote: > Hi Laurent, > Thank you for the review. > Please refer to the comments below. > > On 10/11/2012 11:36 PM, Laurent Pinchart wrote: > > Hi Tomasz, > > > > Thanks for the patch. > > > > On Wednesday 10 October 2012 16:46:41 Tomasz Stanislawski wrote: > >> From: Marek Szyprowski <m.szyprowski@samsung.com> > >> > >> The DMA transfer must be aligned to a specific value. If userptr is not > >> aligned to DMA requirements then unexpected corruptions of the memory may > >> occur before or after a buffer. To prevent such situations, all unligned > >> userptr buffers are rejected at VIDIOC_QBUF. > >> > >> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > >> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> > >> --- > >> drivers/media/v4l2-core/videobuf2-dma-contig.c | 12 ++++++++++++ > >> 1 file changed, 12 insertions(+) > >> > >> diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c > >> b/drivers/media/v4l2-core/videobuf2-dma-contig.c index 2d661fd..571a919 > >> 100644 > >> --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c > >> +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c > >> @@ -493,6 +493,18 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, > >> unsigned long vaddr, struct vm_area_struct *vma; > >> struct sg_table *sgt; > >> unsigned long contig_size; > >> + unsigned long dma_align = dma_get_cache_alignment(); > >> + > >> + /* Only cache aligned DMA transfers are reliable */ > >> + if (!IS_ALIGNED(vaddr | size, dma_align)) { > >> + pr_debug("user data must be aligned to %lu bytes\n", dma_align); > >> + return ERR_PTR(-EINVAL); > >> + } > > > > Looks good to me. > > > >> + if (!size) { > >> + pr_debug("size is zero\n"); > >> + return ERR_PTR(-EINVAL); > >> + } > > > > Can this happen ? The vb2 core already has > > > > /* Check if the provided plane buffer is large enough */ > > if (planes[plane].length < q->plane_sizes[plane]) { > > ret = -EINVAL; > > goto err; > > } > > > > Unless queue_setup sets plane_sizes to 0 we can't reach vb2_dc_get_userptr. > > > > Yes.. unfortunately, some drivers set plane_size to 0 at queue_setup. > Especially, if REQBUFS is called before any S_FMT. > Maybe it is just a driver bug. That's a driver bug. Planes with size 0 make no sense whatsoever. vb2 should WARN_ON on that and return an error. My guess is that these drivers do not set up a default format as they should. Regards, Hans > However, VB2 makes no sanity check if plane_sizes[] is zero. > I was not able to find in Documentation nor code comments > any explicit statement that plane_size cannot be zero. > > Therefore I have to reject reject a 0-bytes-long user pointer > at vb2_dc_get_userptr before creating an empty scatterlist > and passing it to the DMA layer. > > Regards, > Tomasz Stanislawski > > >> buf = kzalloc(sizeof *buf, GFP_KERNEL); > >> if (!buf) > > >
Hi Tomasz, On Friday 12 October 2012 09:44:05 Tomasz Stanislawski wrote: > On 10/11/2012 11:36 PM, Laurent Pinchart wrote: > > On Wednesday 10 October 2012 16:46:41 Tomasz Stanislawski wrote: > >> From: Marek Szyprowski <m.szyprowski@samsung.com> > >> > >> The DMA transfer must be aligned to a specific value. If userptr is not > >> aligned to DMA requirements then unexpected corruptions of the memory may > >> occur before or after a buffer. To prevent such situations, all unligned > >> userptr buffers are rejected at VIDIOC_QBUF. > >> > >> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> > >> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> > >> --- > >> > >> drivers/media/v4l2-core/videobuf2-dma-contig.c | 12 ++++++++++++ > >> 1 file changed, 12 insertions(+) > >> > >> diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c > >> b/drivers/media/v4l2-core/videobuf2-dma-contig.c index 2d661fd..571a919 > >> 100644 > >> --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c > >> +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c > >> @@ -493,6 +493,18 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, > >> unsigned long vaddr, struct vm_area_struct *vma; > >> > >> struct sg_table *sgt; > >> unsigned long contig_size; > >> > >> + unsigned long dma_align = dma_get_cache_alignment(); > >> + > >> + /* Only cache aligned DMA transfers are reliable */ > >> + if (!IS_ALIGNED(vaddr | size, dma_align)) { > >> + pr_debug("user data must be aligned to %lu bytes\n", dma_align); > >> + return ERR_PTR(-EINVAL); > >> + } > > > > Looks good to me. > > > >> + if (!size) { > >> + pr_debug("size is zero\n"); > >> + return ERR_PTR(-EINVAL); > >> + } > > > > Can this happen ? The vb2 core already has > > > > /* Check if the provided plane buffer is large enough */ > > if (planes[plane].length < q->plane_sizes[plane]) { > > > > ret = -EINVAL; > > goto err; > > > > } > > > > Unless queue_setup sets plane_sizes to 0 we can't reach > > vb2_dc_get_userptr. > > Yes.. unfortunately, some drivers set plane_size to 0 at queue_setup. > Especially, if REQBUFS is called before any S_FMT. > Maybe it is just a driver bug. > > However, VB2 makes no sanity check if plane_sizes[] is zero. > I was not able to find in Documentation nor code comments > any explicit statement that plane_size cannot be zero. > > Therefore I have to reject reject a 0-bytes-long user pointer > at vb2_dc_get_userptr before creating an empty scatterlist > and passing it to the DMA layer. Wouldn't it then be better to add the sanity checks in the core ? > >> buf = kzalloc(sizeof *buf, GFP_KERNEL); > >> if (!buf)
diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c index 2d661fd..571a919 100644 --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c @@ -493,6 +493,18 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr, struct vm_area_struct *vma; struct sg_table *sgt; unsigned long contig_size; + unsigned long dma_align = dma_get_cache_alignment(); + + /* Only cache aligned DMA transfers are reliable */ + if (!IS_ALIGNED(vaddr | size, dma_align)) { + pr_debug("user data must be aligned to %lu bytes\n", dma_align); + return ERR_PTR(-EINVAL); + } + + if (!size) { + pr_debug("size is zero\n"); + return ERR_PTR(-EINVAL); + } buf = kzalloc(sizeof *buf, GFP_KERNEL); if (!buf)