From: Chenyuan Mi cymi20@fudan.edu.cn
[ Upstream commit 6bb8c2d51811eb5e6504f49efe3b089d026009d2 ]
The reference counting issue happens in one exception handling path of nouveau_svmm_bind(). When cli->svm.svmm is null, the function forgets to decrease the refcount of mm increased by get_task_mm(), causing a refcount leak.
Fix this issue by using mmput() to decrease the refcount in the exception handling path.
Also, the function forgets to do check against null when get mm by get_task_mm().
Fix this issue by adding null check after get mm by get_task_mm().
Signed-off-by: Chenyuan Mi cymi20@fudan.edu.cn Signed-off-by: Xiyu Yang xiyuyang19@fudan.edu.cn Signed-off-by: Xin Tan tanxin.ctf@gmail.com Fixes: 822cab6150d3 ("drm/nouveau/svm: check for SVM initialized before migrating") Reviewed-by: Lyude Paul lyude@redhat.com Reviewed-by: Ben Skeggs bskeggs@redhat.com Reviewed-by: Karol Herbst kherbst@redhat.com Signed-off-by: Karol Herbst kherbst@redhat.com Link: https://patchwork.freedesktop.org/patch/msgid/20210907122633.16665-1-cymi20@... Link: https://gitlab.freedesktop.org/drm/nouveau/-/merge_requests/14 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/nouveau/nouveau_svm.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/nouveau/nouveau_svm.c b/drivers/gpu/drm/nouveau/nouveau_svm.c index b0c3422cb01fa..9985bfde015a6 100644 --- a/drivers/gpu/drm/nouveau/nouveau_svm.c +++ b/drivers/gpu/drm/nouveau/nouveau_svm.c @@ -162,10 +162,14 @@ nouveau_svmm_bind(struct drm_device *dev, void *data, */
mm = get_task_mm(current); + if (!mm) { + return -EINVAL; + } mmap_read_lock(mm);
if (!cli->svm.svmm) { mmap_read_unlock(mm); + mmput(mm); return -EINVAL; }