udmabuf: Assert held reservation lock for dma-buf mmapping

When userspace mmaps dma-buf's fd, the dma-buf reservation lock must be
held. Add locking sanity check to the dma-buf mmaping callback to ensure
that the locking assumption won't regress in the future.

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221110201349.351294-4-dmitry.osipenko@collabora.com

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index 2bcdb935a3ac4d2ad6195cf780aec60fad83e39a..283816fbd72fc39b34b17a559950a4c94af08d90 100644 (file)
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -2,6 +2,7 @@
 #include <linux/cred.h>
 #include <linux/device.h>
 #include <linux/dma-buf.h>
+#include <linux/dma-resv.h>
 #include <linux/highmem.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -49,6 +50,8 @@ static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
 {
        struct udmabuf *ubuf = buf->priv;
 
+       dma_resv_assert_held(buf->resv);
+
        if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
                return -EINVAL;