2023-06-14 16:36:19

by Jeffrey Hugo

Subject: [PATCH] accel/qaic: Call DRM helper function to destroy prime GEM

From: Pranjal Ramajor Asha Kanojiya <[email protected]>

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().

drm_prime_gem_destroy() handles this issue and performs the proper clean
up instead of open coding it in the driver.

Fixes: ff13be830333 ("accel/qaic: Add datapath")
Reported-by: Sukrut Bellary <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Suggested-by: Christian König <[email protected]>
Signed-off-by: Pranjal Ramajor Asha Kanojiya <[email protected]>
Reviewed-by: Carl Vanderlip <[email protected]>
Reviewed-by: Jeffrey Hugo <[email protected]>
Signed-off-by: Jeffrey Hugo <[email protected]>
---
drivers/accel/qaic/qaic_data.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c
index e42c1f9ffff8..e9a1cb779b30 100644
--- a/drivers/accel/qaic/qaic_data.c
+++ b/drivers/accel/qaic/qaic_data.c
@@ -23,6 +23,7 @@
#include <linux/wait.h>
#include <drm/drm_file.h>
#include <drm/drm_gem.h>
+#include <drm/drm_prime.h>
#include <drm/drm_print.h>
#include <uapi/drm/qaic_accel.h>

@@ -616,8 +617,7 @@ static void qaic_free_object(struct drm_gem_object *obj)

if (obj->import_attach) {
/* DMABUF/PRIME Path */
- dma_buf_detach(obj->import_attach->dmabuf, obj->import_attach);
- dma_buf_put(obj->import_attach->dmabuf);
+ drm_prime_gem_destroy(obj, NULL);
} else {
/* Private buffer allocation path */
qaic_free_sgt(bo->sgt);
--
2.40.1

2023-06-15 07:32:02

by Christian König

Subject: Re: [PATCH] accel/qaic: Call DRM helper function to destroy prime GEM

Am 14.06.23 um 18:15 schrieb Jeffrey Hugo:
> From: Pranjal Ramajor Asha Kanojiya <[email protected]>
>
> 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().
>
> drm_prime_gem_destroy() handles this issue and performs the proper clean
> up instead of open coding it in the driver.
>
> Fixes: ff13be830333 ("accel/qaic: Add datapath")
> Reported-by: Sukrut Bellary <[email protected]>
> Closes: https://lore.kernel.org/all/[email protected]/
> Suggested-by: Christian König <[email protected]>
> Signed-off-by: Pranjal Ramajor Asha Kanojiya <[email protected]>
> Reviewed-by: Carl Vanderlip <[email protected]>
> Reviewed-by: Jeffrey Hugo <[email protected]>
> Signed-off-by: Jeffrey Hugo <[email protected]>

Reviewed-by: Christian König <[email protected]>

> ---
> drivers/accel/qaic/qaic_data.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c
> index e42c1f9ffff8..e9a1cb779b30 100644
> --- a/drivers/accel/qaic/qaic_data.c
> +++ b/drivers/accel/qaic/qaic_data.c
> @@ -23,6 +23,7 @@
> #include <linux/wait.h>
> #include <drm/drm_file.h>
> #include <drm/drm_gem.h>
> +#include <drm/drm_prime.h>
> #include <drm/drm_print.h>
> #include <uapi/drm/qaic_accel.h>
>
> @@ -616,8 +617,7 @@ static void qaic_free_object(struct drm_gem_object *obj)
>
> if (obj->import_attach) {
> /* DMABUF/PRIME Path */
> - dma_buf_detach(obj->import_attach->dmabuf, obj->import_attach);
> - dma_buf_put(obj->import_attach->dmabuf);
> + drm_prime_gem_destroy(obj, NULL);
> } else {
> /* Private buffer allocation path */
> qaic_free_sgt(bo->sgt);

2023-06-15 15:29:25

by Jeffrey Hugo

Subject: Re: [PATCH] accel/qaic: Call DRM helper function to destroy prime GEM

On 6/15/2023 1:05 AM, Christian König wrote:
>
>
> Am 14.06.23 um 18:15 schrieb Jeffrey Hugo:
>> From: Pranjal Ramajor Asha Kanojiya <[email protected]>
>>
>> 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().
>>
>> drm_prime_gem_destroy() handles this issue and performs the proper clean
>> up instead of open coding it in the driver.
>>
>> Fixes: ff13be830333 ("accel/qaic: Add datapath")
>> Reported-by: Sukrut Bellary <[email protected]>
>> Closes:
>> https://lore.kernel.org/all/[email protected]/
>>
>> Suggested-by: Christian König <[email protected]>
>> Signed-off-by: Pranjal Ramajor Asha Kanojiya <[email protected]>
>> Reviewed-by: Carl Vanderlip <[email protected]>
>> Reviewed-by: Jeffrey Hugo <[email protected]>
>> Signed-off-by: Jeffrey Hugo <[email protected]>
>
> Reviewed-by: Christian König <[email protected]>

Thanks for the guidance and review!

2023-06-20 14:35:17

by Jeffrey Hugo

Subject: Re: [PATCH] accel/qaic: Call DRM helper function to destroy prime GEM

On 6/14/2023 10:15 AM, Jeffrey Hugo wrote:
> From: Pranjal Ramajor Asha Kanojiya <[email protected]>
>
> 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().
>
> drm_prime_gem_destroy() handles this issue and performs the proper clean
> up instead of open coding it in the driver.
>
> Fixes: ff13be830333 ("accel/qaic: Add datapath")
> Reported-by: Sukrut Bellary <[email protected]>
> Closes: https://lore.kernel.org/all/[email protected]/
> Suggested-by: Christian König <[email protected]>
> Signed-off-by: Pranjal Ramajor Asha Kanojiya <[email protected]>
> Reviewed-by: Carl Vanderlip <[email protected]>
> Reviewed-by: Jeffrey Hugo <[email protected]>
> Signed-off-by: Jeffrey Hugo <[email protected]>

Pushed to drm-misc-fixes

-Jeff