[PATCH v2 1/2] drm/msm/a6xx: fix use-after-free of OPP in a6xx_pm_resume

[PATCH v2 1/2] drm/msm/a6xx: fix use-after-free of OPP in a6xx_pm_resume

[Roman Demidov]

The OPP reference obtained via dev_pm_opp_find_freq_ceil() is dropped
with dev_pm_opp_put() before being passed to dev_pm_opp_set_opp(). If
the reference count reaches zero, the OPP object may be freed, leading
to a use-after-free when dev_pm_opp_set_opp() dereferences it.

Fix the order of calls: first use the OPP to set the required
performance state, then release the reference.

Fixes: 5a903a44a984 ("drm/msm/a6xx: Introduce GMU wrapper support")
Signed-off-by: Roman Demidov <roman.demidov.nn@gmail.com>
---
v2: The dev_pm_opp_find_freq_ceil() function returns an OPP object with an
incremented reference count. Dropping this reference via dev_pm_opp_put()
could cause the object to be freed if it is concurrently removed from the
OPP table. Fix this as Sashiko AI <sashiko-bot@kernel.org> suggested.

 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index f9de9329dee3..c827986951cc 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -2177,10 +2177,10 @@ static int a6xx_pm_resume(struct msm_gpu *gpu)
 		ret = PTR_ERR(opp);
 		goto err_set_opp;
 	}
-	dev_pm_opp_put(opp);
 
 	/* Set the core clock and bus bw, having VDD scaling in mind */
 	dev_pm_opp_set_opp(&gpu->pdev->dev, opp);
+	dev_pm_opp_put(opp);
 
 	pm_runtime_resume_and_get(gmu->dev);
 	pm_runtime_resume_and_get(gmu->gxpd);
-- 
2.53.0

[PATCH v2 2/2] drm/msm/a6xx: check pm_runtime_resume_and_get during resume

[Roman Demidov]

The return values of pm_runtime_resume_and_get() calls in a6xx_pm_resume()
are not checked, which can lead to hardware access on suspended devices
and PM reference underflows.

Fix this by checking the return value of each pm_runtime_resume_and_get()
call and properly unwinding the previously acquired resources on failure.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 5a903a44a984 ("drm/msm/a6xx: Introduce GMU wrapper support")
Signed-off-by: Roman Demidov <roman.demidov.nn@gmail.com>
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 38 +++++++++++++++------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index c827986951cc..a6da448ee6c2 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -2175,44 +2175,48 @@ static int a6xx_pm_resume(struct msm_gpu *gpu)
 	opp = dev_pm_opp_find_freq_ceil(&gpu->pdev->dev, &freq);
 	if (IS_ERR(opp)) {
 		ret = PTR_ERR(opp);
-		goto err_set_opp;
+		goto err_unlock;
 	}
 
 	/* Set the core clock and bus bw, having VDD scaling in mind */
 	dev_pm_opp_set_opp(&gpu->pdev->dev, opp);
 	dev_pm_opp_put(opp);
 
-	pm_runtime_resume_and_get(gmu->dev);
-	pm_runtime_resume_and_get(gmu->gxpd);
+	ret = pm_runtime_resume_and_get(gmu->dev);
+	if (ret < 0)
+		goto err_opp_clear;
+	ret = pm_runtime_resume_and_get(gmu->gxpd);
+	if (ret < 0)
+		goto err_put_dev;
 
 	ret = clk_bulk_prepare_enable(gpu->nr_clocks, gpu->grp_clks);
 	if (ret)
-		goto err_bulk_clk;
+		goto err_put_gxpd;
 
 	ret = clk_bulk_prepare_enable(gmu->nr_clocks, gmu->clocks);
 	if (ret) {
 		clk_bulk_disable_unprepare(gpu->nr_clocks, gpu->grp_clks);
-		goto err_bulk_clk;
+		goto err_put_gxpd;
 	}
 
 	if (adreno_is_a619_holi(adreno_gpu))
 		a6xx_sptprac_enable(gmu);
 
-	/* If anything goes south, tear the GPU down piece by piece.. */
-	if (ret) {
-err_bulk_clk:
-		pm_runtime_put(gmu->gxpd);
-		pm_runtime_put(gmu->dev);
-		dev_pm_opp_set_opp(&gpu->pdev->dev, NULL);
-	}
-err_set_opp:
 	mutex_unlock(&a6xx_gpu->gmu.lock);
+	msm_devfreq_resume(gpu);
+	a6xx_llc_activate(a6xx_gpu);
 
-	if (!ret) {
-		msm_devfreq_resume(gpu);
-		a6xx_llc_activate(a6xx_gpu);
-	}
+	return 0;
 
+	/* If anything goes south, tear the GPU down piece by piece.. */
+err_put_gxpd:
+	pm_runtime_put(gmu->gxpd);
+err_put_dev:
+	pm_runtime_put(gmu->dev);
+err_opp_clear:
+	dev_pm_opp_set_opp(&gpu->pdev->dev, NULL);
+err_unlock:
+	mutex_unlock(&a6xx_gpu->gmu.lock);
 	return ret;
 }
 
-- 
2.53.0

Re: [PATCH v2 1/2] drm/msm/a6xx: fix use-after-free of OPP in a6xx_pm_resume

[Dmitry Baryshkov]

On Tue, Sep 29, 2026 at 05:20:58PM +0300, Roman Demidov wrote:
> The OPP reference obtained via dev_pm_opp_find_freq_ceil() is dropped
> with dev_pm_opp_put() before being passed to dev_pm_opp_set_opp(). If
> the reference count reaches zero, the OPP object may be freed, leading
> to a use-after-free when dev_pm_opp_set_opp() dereferences it.
> 
> Fix the order of calls: first use the OPP to set the required
> performance state, then release the reference.
> 
> Fixes: 5a903a44a984 ("drm/msm/a6xx: Introduce GMU wrapper support")
> Signed-off-by: Roman Demidov <roman.demidov.nn@gmail.com>
> ---
> v2: The dev_pm_opp_find_freq_ceil() function returns an OPP object with an
> incremented reference count. Dropping this reference via dev_pm_opp_put()
> could cause the object to be freed if it is concurrently removed from the
> OPP table. Fix this as Sashiko AI <sashiko-bot@kernel.org> suggested.
> 
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry

Re: [PATCH v2 2/2] drm/msm/a6xx: check pm_runtime_resume_and_get during resume

[Dmitry Baryshkov]

On Tue, Sep 29, 2026 at 05:20:59PM +0300, Roman Demidov wrote:
> The return values of pm_runtime_resume_and_get() calls in a6xx_pm_resume()
> are not checked, which can lead to hardware access on suspended devices
> and PM reference underflows.
> 
> Fix this by checking the return value of each pm_runtime_resume_and_get()
> call and properly unwinding the previously acquired resources on failure.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 5a903a44a984 ("drm/msm/a6xx: Introduce GMU wrapper support")
> Signed-off-by: Roman Demidov <roman.demidov.nn@gmail.com>
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 38 +++++++++++++++------------
>  1 file changed, 21 insertions(+), 17 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>


-- 
With best wishes
Dmitry

Re: [PATCH v2 1/2] drm/msm/a6xx: fix use-after-free of OPP in a6xx_pm_resume

[Konrad Dybcio]

On 9/29/26 4:20 PM, Roman Demidov wrote:
> The OPP reference obtained via dev_pm_opp_find_freq_ceil() is dropped
> with dev_pm_opp_put() before being passed to dev_pm_opp_set_opp(). If
> the reference count reaches zero, the OPP object may be freed, leading
> to a use-after-free when dev_pm_opp_set_opp() dereferences it.
> 
> Fix the order of calls: first use the OPP to set the required
> performance state, then release the reference.
> 
> Fixes: 5a903a44a984 ("drm/msm/a6xx: Introduce GMU wrapper support")
> Signed-off-by: Roman Demidov <roman.demidov.nn@gmail.com>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad

Re: [PATCH v2 2/2] drm/msm/a6xx: check pm_runtime_resume_and_get during resume

[Konrad Dybcio]

On 9/29/26 4:20 PM, Roman Demidov wrote:
> The return values of pm_runtime_resume_and_get() calls in a6xx_pm_resume()
> are not checked, which can lead to hardware access on suspended devices
> and PM reference underflows.
> 
> Fix this by checking the return value of each pm_runtime_resume_and_get()
> call and properly unwinding the previously acquired resources on failure.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 5a903a44a984 ("drm/msm/a6xx: Introduce GMU wrapper support")
> Signed-off-by: Roman Demidov <roman.demidov.nn@gmail.com>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad