* [PATCH][next] drm/radeon/nislands_smc.h: Replace one-element array with flexible-array member in struct NISLANDS_SMC_SWSTATE
@ 2021-02-10 23:49 Gustavo A. R. Silva
2021-02-15 18:59 ` Alex Deucher
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2021-02-10 23:49 UTC (permalink / raw)
To: Alex Deucher, Christian König, David Airlie, Daniel Vetter
Cc: amd-gfx, dri-devel, linux-kernel, Gustavo A. R. Silva, linux-hardening
There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].
Use flexible-array member in struct NISLANDS_SMC_SWSTATE, instead of
one-element array.
Also, this helps with the ongoing efforts to enable -Warray-bounds by
fixing the following warnings:
drivers/gpu/drm/radeon/ni_dpm.c: In function ‘ni_convert_power_state_to_smc’:
drivers/gpu/drm/radeon/ni_dpm.c:2521:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
2521 | smc_state->levels[i].dpm2.MaxPS =
| ~~~~~~~~~~~~~~~~~^~~
drivers/gpu/drm/radeon/ni_dpm.c:2523:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
2523 | smc_state->levels[i].dpm2.NearTDPDec = NISLANDS_DPM2_NEAR_TDP_DEC;
| ~~~~~~~~~~~~~~~~~^~~
drivers/gpu/drm/radeon/ni_dpm.c:2524:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
2524 | smc_state->levels[i].dpm2.AboveSafeInc = NISLANDS_DPM2_ABOVE_SAFE_INC;
| ~~~~~~~~~~~~~~~~~^~~
drivers/gpu/drm/radeon/ni_dpm.c:2525:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
2525 | smc_state->levels[i].dpm2.BelowSafeInc = NISLANDS_DPM2_BELOW_SAFE_INC;
| ~~~~~~~~~~~~~~~~~^~~
drivers/gpu/drm/radeon/ni_dpm.c:2526:35: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
2526 | smc_state->levels[i].stateFlags |=
| ^~
drivers/gpu/drm/radeon/ni_dpm.c:2526:35: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
2526 | smc_state->levels[i].stateFlags |=
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~
2527 | ((i != (state->performance_level_count - 1)) && power_boost_limit) ?
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2528 | PPSMC_STATEFLAG_POWERBOOST : 0;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/radeon/ni_dpm.c:2442:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
2442 | smc_state->levels[i + 1].aT = cpu_to_be32(a_t);
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/6023ed54.BfIY+9Uz81I6nq19%25lkp@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/gpu/drm/radeon/nislands_smc.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/radeon/nislands_smc.h b/drivers/gpu/drm/radeon/nislands_smc.h
index 3cf8fc0d83f4..7395cb6b3cac 100644
--- a/drivers/gpu/drm/radeon/nislands_smc.h
+++ b/drivers/gpu/drm/radeon/nislands_smc.h
@@ -134,11 +134,11 @@ typedef struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL NISLANDS_SMC_HW_PERFORMANCE_LEV
struct NISLANDS_SMC_SWSTATE
{
- uint8_t flags;
- uint8_t levelCount;
- uint8_t padding2;
- uint8_t padding3;
- NISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[1];
+ uint8_t flags;
+ uint8_t levelCount;
+ uint8_t padding2;
+ uint8_t padding3;
+ NISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[];
};
typedef struct NISLANDS_SMC_SWSTATE NISLANDS_SMC_SWSTATE;
--
2.27.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH][next] drm/radeon/nislands_smc.h: Replace one-element array with flexible-array member in struct NISLANDS_SMC_SWSTATE
2021-02-10 23:49 [PATCH][next] drm/radeon/nislands_smc.h: Replace one-element array with flexible-array member in struct NISLANDS_SMC_SWSTATE Gustavo A. R. Silva
@ 2021-02-15 18:59 ` Alex Deucher
0 siblings, 0 replies; 2+ messages in thread
From: Alex Deucher @ 2021-02-15 18:59 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Alex Deucher, Christian König, David Airlie, Daniel Vetter,
linux-hardening, Maling list - DRI developers, amd-gfx list,
LKML
On Wed, Feb 10, 2021 at 6:49 PM Gustavo A. R. Silva
<gustavoars@kernel.org> wrote:
>
> There is a regular need in the kernel to provide a way to declare having
> a dynamically sized set of trailing elements in a structure. Kernel code
> should always use “flexible array members”[1] for these cases. The older
> style of one-element or zero-length arrays should no longer be used[2].
>
> Use flexible-array member in struct NISLANDS_SMC_SWSTATE, instead of
> one-element array.
>
> Also, this helps with the ongoing efforts to enable -Warray-bounds by
> fixing the following warnings:
>
> drivers/gpu/drm/radeon/ni_dpm.c: In function ‘ni_convert_power_state_to_smc’:
> drivers/gpu/drm/radeon/ni_dpm.c:2521:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> 2521 | smc_state->levels[i].dpm2.MaxPS =
> | ~~~~~~~~~~~~~~~~~^~~
> drivers/gpu/drm/radeon/ni_dpm.c:2523:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> 2523 | smc_state->levels[i].dpm2.NearTDPDec = NISLANDS_DPM2_NEAR_TDP_DEC;
> | ~~~~~~~~~~~~~~~~~^~~
> drivers/gpu/drm/radeon/ni_dpm.c:2524:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> 2524 | smc_state->levels[i].dpm2.AboveSafeInc = NISLANDS_DPM2_ABOVE_SAFE_INC;
> | ~~~~~~~~~~~~~~~~~^~~
> drivers/gpu/drm/radeon/ni_dpm.c:2525:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> 2525 | smc_state->levels[i].dpm2.BelowSafeInc = NISLANDS_DPM2_BELOW_SAFE_INC;
> | ~~~~~~~~~~~~~~~~~^~~
> drivers/gpu/drm/radeon/ni_dpm.c:2526:35: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> 2526 | smc_state->levels[i].stateFlags |=
> | ^~
> drivers/gpu/drm/radeon/ni_dpm.c:2526:35: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> 2526 | smc_state->levels[i].stateFlags |=
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~
> 2527 | ((i != (state->performance_level_count - 1)) && power_boost_limit) ?
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 2528 | PPSMC_STATEFLAG_POWERBOOST : 0;
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/radeon/ni_dpm.c:2442:20: warning: array subscript 1 is above array bounds of ‘NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’ {aka ‘struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL[1]’} [-Warray-bounds]
> 2442 | smc_state->levels[i + 1].aT = cpu_to_be32(a_t);
>
> [1] https://en.wikipedia.org/wiki/Flexible_array_member
> [2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
>
> Link: https://github.com/KSPP/linux/issues/79
> Link: https://github.com/KSPP/linux/issues/109
> Build-tested-by: kernel test robot <lkp@intel.com>
> Link: https://lore.kernel.org/lkml/6023ed54.BfIY+9Uz81I6nq19%25lkp@intel.com/
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Applied. Thanks!
Alex
> ---
> drivers/gpu/drm/radeon/nislands_smc.h | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/nislands_smc.h b/drivers/gpu/drm/radeon/nislands_smc.h
> index 3cf8fc0d83f4..7395cb6b3cac 100644
> --- a/drivers/gpu/drm/radeon/nislands_smc.h
> +++ b/drivers/gpu/drm/radeon/nislands_smc.h
> @@ -134,11 +134,11 @@ typedef struct NISLANDS_SMC_HW_PERFORMANCE_LEVEL NISLANDS_SMC_HW_PERFORMANCE_LEV
>
> struct NISLANDS_SMC_SWSTATE
> {
> - uint8_t flags;
> - uint8_t levelCount;
> - uint8_t padding2;
> - uint8_t padding3;
> - NISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[1];
> + uint8_t flags;
> + uint8_t levelCount;
> + uint8_t padding2;
> + uint8_t padding3;
> + NISLANDS_SMC_HW_PERFORMANCE_LEVEL levels[];
> };
>
> typedef struct NISLANDS_SMC_SWSTATE NISLANDS_SMC_SWSTATE;
> --
> 2.27.0
>
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
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2021-02-10 23:49 [PATCH][next] drm/radeon/nislands_smc.h: Replace one-element array with flexible-array member in struct NISLANDS_SMC_SWSTATE Gustavo A. R. Silva
2021-02-15 18:59 ` Alex Deucher
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