2023-01-08 21:17:12

by Dmitry Osipenko

Subject: [PATCH v1] drm/shmem-helper: Remove another errant put in error path

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: [email protected]
Signed-off-by: Dmitry Osipenko <[email protected]>
---
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 f21f47737817..8b20b41497e8 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -624,11 +624,14 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct
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);
+
+ /* Drop the reference drm_gem_mmap_obj() acquired.*/
+ if (!ret)
+ drm_gem_object_put(obj);

- return dma_buf_mmap(obj->dma_buf, vma, 0);
+ return ret;
}

ret = drm_gem_shmem_get_pages(shmem);
--
2.38.1

2023-01-26 12:36:24

by Dmitry Osipenko

Subject: Re: [PATCH v1] drm/shmem-helper: Remove another errant put in error path

On 1/9/23 00:13, Dmitry Osipenko wrote:
> 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: [email protected]
> Signed-off-by: Dmitry Osipenko <[email protected]>
> ---
> 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 f21f47737817..8b20b41497e8 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -624,11 +624,14 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct
> 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);
> +
> + /* Drop the reference drm_gem_mmap_obj() acquired.*/
> + if (!ret)
> + drm_gem_object_put(obj);
>
> - return dma_buf_mmap(obj->dma_buf, vma, 0);
> + return ret;
> }
>
> ret = drm_gem_shmem_get_pages(shmem);

Rob, is this change still looking good to you? r-b? Thanks!

--
Best regards,
Dmitry

2023-02-16 15:35:18

by Rob Clark

Subject: Re: [PATCH v1] drm/shmem-helper: Remove another errant put in error path

On Sun, Jan 8, 2023 at 1:13 PM Dmitry Osipenko
<[email protected]> wrote:
>
> 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: [email protected]
> Signed-off-by: Dmitry Osipenko <[email protected]>

Reviewed-by: Rob Clark <[email protected]>

> ---
> 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 f21f47737817..8b20b41497e8 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -624,11 +624,14 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct
> 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);
> +
> + /* Drop the reference drm_gem_mmap_obj() acquired.*/
> + if (!ret)
> + drm_gem_object_put(obj);
>
> - return dma_buf_mmap(obj->dma_buf, vma, 0);
> + return ret;
> }
>
> ret = drm_gem_shmem_get_pages(shmem);
> --
> 2.38.1
>

2023-02-26 23:51:45

by Dmitry Osipenko

Subject: Re: [PATCH v1] drm/shmem-helper: Remove another errant put in error path

On 2/16/23 18:35, Rob Clark wrote:
> On Sun, Jan 8, 2023 at 1:13 PM Dmitry Osipenko
> <[email protected]> wrote:
>>
>> 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: [email protected]
>> Signed-off-by: Dmitry Osipenko <[email protected]>
>
> Reviewed-by: Rob Clark <[email protected]>

Applied to misc-fixes

--
Best regards,
Dmitry