From 684c7372bbd6447c2e86a2a84e97a1478604d21f Mon Sep 17 00:00:00 2001 From: Dmitry Osipenko Date: Mon, 9 Jan 2023 00:13:11 +0300 Subject: [PATCH] drm/shmem-helper: Remove another errant put in error path commit ee9adb7a45516cfa536ca92253d7ae59d56db9e4 upstream. drm_gem_shmem_mmap() doesn't own reference in error code path, resulting in the dma-buf shmem GEM object getting prematurely freed leading to a later use-after-free. Fixes: f49a51bfdc8e ("drm/shme-helpers: Fix dma_buf_mmap forwarding bug") Cc: stable@vger.kernel.org Signed-off-by: Dmitry Osipenko Reviewed-by: Rob Clark Link: https://patchwork.freedesktop.org/patch/msgid/20230108211311.3950107-1-dmitry.osipenko@collabora.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_gem_shmem_helper.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index c56656a95cf9..b7bb5610dfe2 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -614,11 +614,14 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) int ret; if (obj->import_attach) { - /* Drop the reference drm_gem_mmap_obj() acquired.*/ - drm_gem_object_put(obj); vma->vm_private_data = NULL; + ret = dma_buf_mmap(obj->dma_buf, vma, 0); - return dma_buf_mmap(obj->dma_buf, vma, 0); + /* Drop the reference drm_gem_mmap_obj() acquired.*/ + if (!ret) + drm_gem_object_put(obj); + + return ret; } shmem = to_drm_gem_shmem_obj(obj);