Re: [PATCH] accel/qaic: Fix dereferencing freed memory
From: Pranjal Ramajor Asha Kanojiya
Date: Mon Jun 12 2023 - 08:44:40 EST
On 6/10/2023 7:42 AM, Sukrut Bellary wrote:
smatch warning:
drivers/accel/qaic/qaic_data.c:620 qaic_free_object() error:
dereferencing freed memory 'obj->import_attach'
obj->import_attach is detached and freed using dma_buf_detach().
But used after free to decrease the dmabuf ref count using
dma_buf_put().
Fixes: ff13be830333 ("accel/qaic: Add datapath")
Signed-off-by: Sukrut Bellary <sukrut.bellary@xxxxxxxxx>
---
drivers/accel/qaic/qaic_data.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c
index e42c1f9ffff8..7cba4d680ea8 100644
--- a/drivers/accel/qaic/qaic_data.c
+++ b/drivers/accel/qaic/qaic_data.c
@@ -613,11 +613,13 @@ static int qaic_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_struc
static void qaic_free_object(struct drm_gem_object *obj)
{
struct qaic_bo *bo = to_qaic_bo(obj);
+ struct dma_buf *dmabuf;
if (obj->import_attach) {
/* DMABUF/PRIME Path */
+ dmabuf = obj->import_attach->dmabuf;
dma_buf_detach(obj->import_attach->dmabuf, obj->import_attach);
- dma_buf_put(obj->import_attach->dmabuf);
+ dma_buf_put(dmabuf);
} else {
/* Private buffer allocation path */
qaic_free_sgt(bo->sgt);
Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@xxxxxxxxxxx>