From d81e870d5afa1b0a95ea94c4052d3c7e973fae8c Mon Sep 17 00:00:00 2001 From: Marek Szyprowski Date: Tue, 12 Jun 2012 10:18:16 -0300 Subject: [PATCH] [media] v4l: vb2-dma-contig: fail if user ptr buffer is not correctly aligned 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 Acked-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- 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 b35f38e..27de1bb 100644 --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c @@ -491,6 +491,18 @@ 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) -- 2.7.4