2023-12-13 14:47:11

by Donald Robson

Subject: [PATCH 2/2] drm/imagination: Fix error path in pvr_vm_create_context

It is possible to double free the vm_ctx->mmu_ctx object in this
function.

    630 err_page_table_destroy:
--> 631         pvr_mmu_context_destroy(vm_ctx->mmu_ctx);

The pvr_vm_context_put() function does:

        kref_put(&vm_ctx->ref_count, pvr_vm_context_release);

Here the pvr_vm_context_release() will call:

        pvr_mmu_context_destroy(vm_ctx->mmu_ctx);

Refactor to an unwind style.

Reported-by: Dan Carpenter <[email protected]>
Signed-off-by: Donald Robson <[email protected]>
---
drivers/gpu/drm/imagination/pvr_vm.c | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/imagination/pvr_vm.c b/drivers/gpu/drm/imagination/pvr_vm.c
index 432168aba577..93155eccc50d 100644
--- a/drivers/gpu/drm/imagination/pvr_vm.c
+++ b/drivers/gpu/drm/imagination/pvr_vm.c
@@ -598,23 +598,12 @@ pvr_vm_create_context(struct pvr_device *pvr_dev, bool is_userspace_context)
if (!vm_ctx)
return ERR_PTR(-ENOMEM);

- drm_gem_private_object_init(&pvr_dev->base, &vm_ctx->dummy_gem, 0);
-
vm_ctx->pvr_dev = pvr_dev;
- kref_init(&vm_ctx->ref_count);
- mutex_init(&vm_ctx->lock);
-
- drm_gpuvm_init(&vm_ctx->gpuvm_mgr,
- is_userspace_context ? "PowerVR-user-VM" : "PowerVR-FW-VM",
- 0, &pvr_dev->base, &vm_ctx->dummy_gem,
- 0, 1ULL << device_addr_bits, 0, 0, &pvr_vm_gpuva_ops);

vm_ctx->mmu_ctx = pvr_mmu_context_create(pvr_dev);
err = PTR_ERR_OR_ZERO(vm_ctx->mmu_ctx);
- if (err) {
- vm_ctx->mmu_ctx = NULL;
- goto err_put_ctx;
- }
+ if (err)
+ goto err_free;

if (is_userspace_context) {
err = pvr_fw_object_create(pvr_dev, sizeof(struct rogue_fwif_fwmemcontext),
@@ -625,13 +614,22 @@ pvr_vm_create_context(struct pvr_device *pvr_dev, bool is_userspace_context)
goto err_page_table_destroy;
}

+ drm_gem_private_object_init(&pvr_dev->base, &vm_ctx->dummy_gem, 0);
+ drm_gpuvm_init(&vm_ctx->gpuvm_mgr,
+ is_userspace_context ? "PowerVR-user-VM" : "PowerVR-FW-VM",
+ 0, &pvr_dev->base, &vm_ctx->dummy_gem,
+ 0, 1ULL << device_addr_bits, 0, 0, &pvr_vm_gpuva_ops);
+
+ mutex_init(&vm_ctx->lock);
+ kref_init(&vm_ctx->ref_count);
+
return vm_ctx;

err_page_table_destroy:
pvr_mmu_context_destroy(vm_ctx->mmu_ctx);

-err_put_ctx:
- pvr_vm_context_put(vm_ctx);
+err_free:
+ kfree(vm_ctx);

return ERR_PTR(err);
}
--
2.25.1

2023-12-13 14:49:14

by Dan Carpenter

Subject: Re: [PATCH 2/2] drm/imagination: Fix error path in pvr_vm_create_context

Thanks so much.

Reviewed-by: Dan Carpenter <[email protected]>

regards,
dan carpenter

2023-12-15 13:13:52

by Maxime Ripard

Subject: Re: (subset) [PATCH 2/2] drm/imagination: Fix error path in pvr_vm_create_context

On Wed, 13 Dec 2023 14:44:31 +0000, Donald Robson wrote:
> It is possible to double free the vm_ctx->mmu_ctx object in this
> function.
>
>     630 err_page_table_destroy:
> --> 631         pvr_mmu_context_destroy(vm_ctx->mmu_ctx);
>
> The pvr_vm_context_put() function does:
>
> [...]

Applied to drm/drm-misc (drm-misc-next-fixes).

Thanks!
Maxime