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().

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@vger.kernel.org
Co-developed-by: Natalia Petrova <n.petrova@fintech.ru>
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>

---
 drivers/gpu/drm/radeon/ci_dpm.c | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)
  

[Public]

> -----Original Message-----
> From: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
> Sent: Monday, April 3, 2023 2:28 PM
> To: Deucher, Alexander <Alexander.Deucher@amd.com>
> Cc: Nikita Zhandarovich <n.zhandarovich@fintech.ru>; Koenig, Christian
> <Christian.Koenig@amd.com>; Pan, Xinhui <Xinhui.Pan@amd.com>; David
> Airlie <airlied@gmail.com>; Daniel Vetter <daniel@ffwll.ch>; amd-
> gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux-
> kernel@vger.kernel.org; lvc-project@linuxtesting.org
> 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@vger.kernel.org
> Co-developed-by: Natalia Petrova <n.petrova@fintech.ru>
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
> 
> ---
>  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;
  

On 4/11/23 14:11, Deucher, Alexander wrote:
> [Public]
> 
>> -----Original Message-----
>> From: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
>> Sent: Monday, April 3, 2023 2:28 PM
>> To: Deucher, Alexander <Alexander.Deucher@amd.com>
>> Cc: Nikita Zhandarovich <n.zhandarovich@fintech.ru>; Koenig, Christian
>> <Christian.Koenig@amd.com>; Pan, Xinhui <Xinhui.Pan@amd.com>; David
>> Airlie <airlied@gmail.com>; Daniel Vetter <daniel@ffwll.ch>; amd-
>> gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux-
>> kernel@vger.kernel.org; lvc-project@linuxtesting.org
>> 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@vger.kernel.org
>> Co-developed-by: Natalia Petrova <n.petrova@fintech.ru>
>> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
>>
>> ---
>>  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;


I think you are correct when it comes to ensuring we deal with memory
issues in ci_dpm_init().

However, I could use some direction on how to deal with the problem of
freeing only previously allocated resources. For instance, once
ci_parse_power_table() fails, it is not clear what we should and should
not free.

I wanna point out that in this case I would like to fix both double and
uninitialized free issues as it can also lead to undefined behavior.

Thanks for your patience,
Nikita
  

On Wed, Apr 12, 2023 at 8:39 AM Nikita Zhandarovich
<n.zhandarovich@fintech.ru> wrote:
>
>
>
> On 4/11/23 14:11, Deucher, Alexander wrote:
> > [Public]
> >
> >> -----Original Message-----
> >> From: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
> >> Sent: Monday, April 3, 2023 2:28 PM
> >> To: Deucher, Alexander <Alexander.Deucher@amd.com>
> >> Cc: Nikita Zhandarovich <n.zhandarovich@fintech.ru>; Koenig, Christian
> >> <Christian.Koenig@amd.com>; Pan, Xinhui <Xinhui.Pan@amd.com>; David
> >> Airlie <airlied@gmail.com>; Daniel Vetter <daniel@ffwll.ch>; amd-
> >> gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux-
> >> kernel@vger.kernel.org; lvc-project@linuxtesting.org
> >> 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@vger.kernel.org
> >> Co-developed-by: Natalia Petrova <n.petrova@fintech.ru>
> >> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
> >>
> >> ---
> >>  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;
>
>
> I think you are correct when it comes to ensuring we deal with memory
> issues in ci_dpm_init().
>
> However, I could use some direction on how to deal with the problem of
> freeing only previously allocated resources. For instance, once
> ci_parse_power_table() fails, it is not clear what we should and should
> not free.

You'll want to free any memory allocated in ci_dpm_init().  Any of the
functions called from that function should clean themselves up if they
allocate any memory, but if not, they should be fixed.

Alex


>
> I wanna point out that in this case I would like to fix both double and
> uninitialized free issues as it can also lead to undefined behavior.
>
> Thanks for your patience,
> Nikita