RE: [PATCH] radeon: avoid double free in ci_dpm_init()

[Deucher, Alexander]

[Public]

> -----Original Message-----
> From: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>
> Sent: Monday, April 3, 2023 2:28 PM
> To: Deucher, Alexander <Alexander.Deucher@xxxxxxx>
> Cc: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>; Koenig, Christian
> <Christian.Koenig@xxxxxxx>; Pan, Xinhui <Xinhui.Pan@xxxxxxx>; David
> Airlie <airlied@xxxxxxxxx>; Daniel Vetter <daniel@xxxxxxxx>; amd-
> gfx@xxxxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; lvc-project@xxxxxxxxxxxxxxxx
> Subject: [PATCH] radeon: avoid double free in ci_dpm_init()
> 
> There are several calls to ci_dpm_fini() in ci_dpm_init() when there occur
> errors in functions like r600_parse_extended_power_table().
> This is harmful as it can lead to double free situations: for instance,
> r600_parse_extended_power_table() will call for
> r600_free_extended_power_table() as will ci_dpm_fini(), both of which will
> try to free resources.
> Other drivers do not call *_dpm_fini functions from their respective
> *_dpm_init calls - neither should cpm_dpm_init().
> 
> Fix this by removing extra calls to ci_dpm_fini().

You can't just drop the calls to fini().  You'll need to properly unwind to avoid leaking memory.

Alex

> 
> Found by Linux Verification Center (linuxtesting.org) with static analysis tool
> SVACE.
> 
> Fixes: cc8dbbb4f62a ("drm/radeon: add dpm support for CI dGPUs (v2)")
> Cc: stable@xxxxxxxxxxxxxxx
> Co-developed-by: Natalia Petrova <n.petrova@xxxxxxxxxx>
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>
> 
> ---
>  drivers/gpu/drm/radeon/ci_dpm.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/radeon/ci_dpm.c
> b/drivers/gpu/drm/radeon/ci_dpm.c index 8ef25ab305ae..7b77d4c93f1d
> 100644
> --- a/drivers/gpu/drm/radeon/ci_dpm.c
> +++ b/drivers/gpu/drm/radeon/ci_dpm.c
> @@ -5677,28 +5677,20 @@ int ci_dpm_init(struct radeon_device *rdev)
>  	pi->pcie_lane_powersaving.min = 16;
> 
>  	ret = ci_get_vbios_boot_values(rdev, &pi->vbios_boot_state);
> -	if (ret) {
> -		ci_dpm_fini(rdev);
> +	if (ret)
>  		return ret;
> -	}
> 
>  	ret = r600_get_platform_caps(rdev);
> -	if (ret) {
> -		ci_dpm_fini(rdev);
> +	if (ret)
>  		return ret;
> -	}
> 
>  	ret = r600_parse_extended_power_table(rdev);
> -	if (ret) {
> -		ci_dpm_fini(rdev);
> +	if (ret)
>  		return ret;
> -	}
> 
>  	ret = ci_parse_power_table(rdev);
> -	if (ret) {
> -		ci_dpm_fini(rdev);
> +	if (ret)
>  		return ret;
> -	}
> 
>  	pi->dll_default_on = false;
>  	pi->sram_end = SMC_RAM_END;
> @@ -5749,10 +5741,8 @@ int ci_dpm_init(struct radeon_device *rdev)
>  		kcalloc(4,
>  			sizeof(struct
> radeon_clock_voltage_dependency_entry),
>  			GFP_KERNEL);
> -	if (!rdev-
> >pm.dpm.dyn_state.vddc_dependency_on_dispclk.entries) {
> -		ci_dpm_fini(rdev);
> +	if (!rdev-
> >pm.dpm.dyn_state.vddc_dependency_on_dispclk.entries)
>  		return -ENOMEM;
> -	}
>  	rdev->pm.dpm.dyn_state.vddc_dependency_on_dispclk.count = 4;
>  	rdev-
> >pm.dpm.dyn_state.vddc_dependency_on_dispclk.entries[0].clk = 0;
>  	rdev-
> >pm.dpm.dyn_state.vddc_dependency_on_dispclk.entries[0].v = 0;