On 6/12/2023 8:39 PM, Jeffrey Hugo wrote:
On 6/12/2023 7:21 AM, Christian König wrote:
Am 12.06.23 um 15:03 schrieb Pranjal Ramajor Asha Kanojiya:
On 6/12/2023 4:52 PM, Christian König wrote:
Am 10.06.23 um 04:12 schrieb Sukrut Bellary:
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;
Maybe move that variable into the if.
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);
I strongly assume you are not using the GEM prime helpers for this?
Christian.
Driver uses drm_gem_prime_fd_to_handle() helper function but it also
registers for ->gem_prime_import() which is internally called by
drm_gem_prime_fd_to_handle(). All the operations done in
gem_prime_import() are undone here.
Then why don't you use drm_prime_gem_destroy() which is the cleanup
helper for imports created by ->gem_prime_import() ?
That looks pretty much identical to what you do here manually.
I think destroy() wasn't used because we are new to DRM and sometimes
confused by the multitude of options. I appreciate the suggestion and
will follow up to see if destroy() will work here, or identify what
would prevent the use of it.
-Jeff
Thank you Christian for your suggestion. I agree with you driver can use
drm_prime_gem_destroy() here.
