When using mmap() on a prime imported buffer allocated by a
different driver (such as imx-drm) the later munmap() does
not correctly decrement the refcount of the original enaviv_gem_object,
leading to a leak.
Signed-off-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c
index f24dd21..28a01b8 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c
@@ -93,7 +93,25 @@ static void *etnaviv_gem_prime_vmap_impl(struct etnaviv_gem_object *etnaviv_obj)
static int etnaviv_gem_prime_mmap_obj(struct etnaviv_gem_object *etnaviv_obj,
struct vm_area_struct *vma)
{
- return dma_buf_mmap(etnaviv_obj->base.dma_buf, vma, 0);
+ int ret;
+
+ ret = dma_buf_mmap(etnaviv_obj->base.dma_buf, vma, 0);
+
+ /* drm_gem_mmap_obj() has already been called before this function
+ * and has incremented our refcount, expecting it to be decremented
+ * on unmap() via drm_gem_vm_close().
+ * However dma_buf_mmap() invokes drm_gem_cma_prime_mmap()
+ * that ends up updating the vma->vma_private_data to point to the
+ * dma_buf's gem object.
+ * Hence our gem object here will not have its refcount decremented
+ * when userspace does unmap().
+ * So decrement the refcount here to avoid a memory leak if the dma
+ * buf mapping was successful.
+ */
+ if (!ret)
+ drm_gem_object_put_unlocked(&etnaviv_obj->base);
+
+ return ret;
}
static const struct etnaviv_gem_ops etnaviv_gem_prime_ops = {
--
1.9.1
