* [PATCH] drm/amdgpu/smu10: Replace one-element array and use struct_size() helper
@ 2020-05-19 22:55 Gustavo A. R. Silva
2020-05-20 7:42 ` Christian König
0 siblings, 1 reply; 5+ messages in thread
From: Gustavo A. R. Silva @ 2020-05-19 22:55 UTC (permalink / raw)
To: Evan Quan, Alex Deucher, Christian König, David Airlie,
Daniel Vetter
Cc: Gustavo A. R. Silva, dri-devel, amd-gfx, linux-kernel
The current codebase makes use of one-element arrays in the following
form:
struct something {
int length;
u8 data[1];
};
struct something *instance;
instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL);
instance->length = size;
memcpy(instance->data, source, size);
but the preferred mechanism to declare variable-length types such as
these ones is a flexible array member[1][2], introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on. So, replace
the one-element array with a flexible-array member.
Also, make use of the new struct_size() helper to properly calculate the
size of struct smu10_voltage_dependency_table.
This issue was found with the help of Coccinelle and, audited and fixed
_manually_.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c | 6 ++----
drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h | 2 +-
2 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
index 246bb9ac557d8..c9cfe90a29471 100644
--- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
+++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
@@ -410,12 +410,10 @@ static int smu10_get_clock_voltage_dependency_table(struct pp_hwmgr *hwmgr,
struct smu10_voltage_dependency_table **pptable,
uint32_t num_entry, const DpmClock_t *pclk_dependency_table)
{
- uint32_t table_size, i;
+ uint32_t i;
struct smu10_voltage_dependency_table *ptable;
- table_size = sizeof(uint32_t) + sizeof(struct smu10_voltage_dependency_table) * num_entry;
- ptable = kzalloc(table_size, GFP_KERNEL);
-
+ ptable = kzalloc(struct_size(ptable, entries, num_entry), GFP_KERNEL);
if (NULL == ptable)
return -ENOMEM;
diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h
index 1fb296a996f3a..0f969de10fabc 100644
--- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h
+++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h
@@ -192,7 +192,7 @@ struct smu10_clock_voltage_dependency_record {
struct smu10_voltage_dependency_table {
uint32_t count;
- struct smu10_clock_voltage_dependency_record entries[1];
+ struct smu10_clock_voltage_dependency_record entries[];
};
struct smu10_clock_voltage_information {
--
2.26.2
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^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] drm/amdgpu/smu10: Replace one-element array and use struct_size() helper
2020-05-19 22:55 [PATCH] drm/amdgpu/smu10: Replace one-element array and use struct_size() helper Gustavo A. R. Silva
@ 2020-05-20 7:42 ` Christian König
2020-05-20 18:17 ` Alex Deucher
2020-05-22 17:51 ` Gustavo A. R. Silva
0 siblings, 2 replies; 5+ messages in thread
From: Christian König @ 2020-05-20 7:42 UTC (permalink / raw)
To: Gustavo A. R. Silva, Evan Quan, Alex Deucher, David Airlie,
Daniel Vetter
Cc: Gustavo A. R. Silva, dri-devel, amd-gfx, linux-kernel
Am 20.05.20 um 00:55 schrieb Gustavo A. R. Silva:
> The current codebase makes use of one-element arrays in the following
> form:
>
> struct something {
> int length;
> u8 data[1];
> };
>
> struct something *instance;
>
> instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL);
> instance->length = size;
> memcpy(instance->data, source, size);
>
> but the preferred mechanism to declare variable-length types such as
> these ones is a flexible array member[1][2], introduced in C99:
>
> struct foo {
> int stuff;
> struct boo array[];
> };
>
> By making use of the mechanism above, we will get a compiler warning
> in case the flexible array does not occur last in the structure, which
> will help us prevent some kind of undefined behavior bugs from being
> inadvertently introduced[3] to the codebase from now on. So, replace
> the one-element array with a flexible-array member.
>
> Also, make use of the new struct_size() helper to properly calculate the
> size of struct smu10_voltage_dependency_table.
>
> This issue was found with the help of Coccinelle and, audited and fixed
> _manually_.
>
> [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgcc.gnu.org%2Fonlinedocs%2Fgcc%2FZero-Length.html&data=02%7C01%7Cchristian.koenig%40amd.com%7C8a400bdb88924a1d951508d7fc471966%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637255254622039268&sdata=ILOPPn17c%2B3oyLLdh%2BgH2b%2B8RdhWuTFGxruRD7GUHOo%3D&reserved=0
> [2] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FKSPP%2Flinux%2Fissues%2F21&data=02%7C01%7Cchristian.koenig%40amd.com%7C8a400bdb88924a1d951508d7fc471966%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637255254622039268&sdata=lCr5Otij55Snq27BDp4RmtW4hNhOS%2Bm4vSUOOAz07XA%3D&reserved=0
> [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
>
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Christian König <christian.koenig@amd.com>
May I suggest that we add a section how to correctly do this to
Documentation/process/coding-style.rst or similar document?
I've seen a bunch of different approaches and some even doesn't work
with some gcc versions and result in a broken binary.
Thanks,
Christian.
> ---
> drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c | 6 ++----
> drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h | 2 +-
> 2 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
> index 246bb9ac557d8..c9cfe90a29471 100644
> --- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
> +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
> @@ -410,12 +410,10 @@ static int smu10_get_clock_voltage_dependency_table(struct pp_hwmgr *hwmgr,
> struct smu10_voltage_dependency_table **pptable,
> uint32_t num_entry, const DpmClock_t *pclk_dependency_table)
> {
> - uint32_t table_size, i;
> + uint32_t i;
> struct smu10_voltage_dependency_table *ptable;
>
> - table_size = sizeof(uint32_t) + sizeof(struct smu10_voltage_dependency_table) * num_entry;
> - ptable = kzalloc(table_size, GFP_KERNEL);
> -
> + ptable = kzalloc(struct_size(ptable, entries, num_entry), GFP_KERNEL);
> if (NULL == ptable)
> return -ENOMEM;
>
> diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h
> index 1fb296a996f3a..0f969de10fabc 100644
> --- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h
> +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h
> @@ -192,7 +192,7 @@ struct smu10_clock_voltage_dependency_record {
>
> struct smu10_voltage_dependency_table {
> uint32_t count;
> - struct smu10_clock_voltage_dependency_record entries[1];
> + struct smu10_clock_voltage_dependency_record entries[];
> };
>
> struct smu10_clock_voltage_information {
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^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] drm/amdgpu/smu10: Replace one-element array and use struct_size() helper
2020-05-20 7:42 ` Christian König
@ 2020-05-20 18:17 ` Alex Deucher
2020-05-22 17:51 ` Gustavo A. R. Silva
1 sibling, 0 replies; 5+ messages in thread
From: Alex Deucher @ 2020-05-20 18:17 UTC (permalink / raw)
To: Christian König
Cc: Gustavo A. R. Silva, David Airlie, Gustavo A. R. Silva,
Maling list - DRI developers, LKML, amd-gfx list, Alex Deucher,
Evan Quan
Applied. thanks!
Alex
On Wed, May 20, 2020 at 3:42 AM Christian König
<christian.koenig@amd.com> wrote:
>
> Am 20.05.20 um 00:55 schrieb Gustavo A. R. Silva:
> > The current codebase makes use of one-element arrays in the following
> > form:
> >
> > struct something {
> > int length;
> > u8 data[1];
> > };
> >
> > struct something *instance;
> >
> > instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL);
> > instance->length = size;
> > memcpy(instance->data, source, size);
> >
> > but the preferred mechanism to declare variable-length types such as
> > these ones is a flexible array member[1][2], introduced in C99:
> >
> > struct foo {
> > int stuff;
> > struct boo array[];
> > };
> >
> > By making use of the mechanism above, we will get a compiler warning
> > in case the flexible array does not occur last in the structure, which
> > will help us prevent some kind of undefined behavior bugs from being
> > inadvertently introduced[3] to the codebase from now on. So, replace
> > the one-element array with a flexible-array member.
> >
> > Also, make use of the new struct_size() helper to properly calculate the
> > size of struct smu10_voltage_dependency_table.
> >
> > This issue was found with the help of Coccinelle and, audited and fixed
> > _manually_.
> >
> > [1] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgcc.gnu.org%2Fonlinedocs%2Fgcc%2FZero-Length.html&data=02%7C01%7Cchristian.koenig%40amd.com%7C8a400bdb88924a1d951508d7fc471966%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637255254622039268&sdata=ILOPPn17c%2B3oyLLdh%2BgH2b%2B8RdhWuTFGxruRD7GUHOo%3D&reserved=0
> > [2] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FKSPP%2Flinux%2Fissues%2F21&data=02%7C01%7Cchristian.koenig%40amd.com%7C8a400bdb88924a1d951508d7fc471966%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637255254622039268&sdata=lCr5Otij55Snq27BDp4RmtW4hNhOS%2Bm4vSUOOAz07XA%3D&reserved=0
> > [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
> >
> > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>
> Acked-by: Christian König <christian.koenig@amd.com>
>
> May I suggest that we add a section how to correctly do this to
> Documentation/process/coding-style.rst or similar document?
>
> I've seen a bunch of different approaches and some even doesn't work
> with some gcc versions and result in a broken binary.
>
> Thanks,
> Christian.
>
> > ---
> > drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c | 6 ++----
> > drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h | 2 +-
> > 2 files changed, 3 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
> > index 246bb9ac557d8..c9cfe90a29471 100644
> > --- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
> > +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.c
> > @@ -410,12 +410,10 @@ static int smu10_get_clock_voltage_dependency_table(struct pp_hwmgr *hwmgr,
> > struct smu10_voltage_dependency_table **pptable,
> > uint32_t num_entry, const DpmClock_t *pclk_dependency_table)
> > {
> > - uint32_t table_size, i;
> > + uint32_t i;
> > struct smu10_voltage_dependency_table *ptable;
> >
> > - table_size = sizeof(uint32_t) + sizeof(struct smu10_voltage_dependency_table) * num_entry;
> > - ptable = kzalloc(table_size, GFP_KERNEL);
> > -
> > + ptable = kzalloc(struct_size(ptable, entries, num_entry), GFP_KERNEL);
> > if (NULL == ptable)
> > return -ENOMEM;
> >
> > diff --git a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h
> > index 1fb296a996f3a..0f969de10fabc 100644
> > --- a/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h
> > +++ b/drivers/gpu/drm/amd/powerplay/hwmgr/smu10_hwmgr.h
> > @@ -192,7 +192,7 @@ struct smu10_clock_voltage_dependency_record {
> >
> > struct smu10_voltage_dependency_table {
> > uint32_t count;
> > - struct smu10_clock_voltage_dependency_record entries[1];
> > + struct smu10_clock_voltage_dependency_record entries[];
> > };
> >
> > struct smu10_clock_voltage_information {
>
> _______________________________________________
> amd-gfx mailing list
> amd-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] drm/amdgpu/smu10: Replace one-element array and use struct_size() helper
2020-05-20 7:42 ` Christian König
2020-05-20 18:17 ` Alex Deucher
@ 2020-05-22 17:51 ` Gustavo A. R. Silva
2020-05-22 17:54 ` Alex Deucher
1 sibling, 1 reply; 5+ messages in thread
From: Gustavo A. R. Silva @ 2020-05-22 17:51 UTC (permalink / raw)
To: Christian König
Cc: Gustavo A. R. Silva, David Airlie, linux-kernel, dri-devel,
amd-gfx, Alex Deucher, Evan Quan
On Wed, May 20, 2020 at 09:42:27AM +0200, Christian König wrote:
> >
> > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>
> Acked-by: Christian König <christian.koenig@amd.com>
>
> May I suggest that we add a section how to correctly do this to
> Documentation/process/coding-style.rst or similar document?
>
That's already on my list. :)
> I've seen a bunch of different approaches and some even doesn't work with
> some gcc versions and result in a broken binary.
>
Do you have an example of that one that doesn't work with some GCC
versions? It'd be interesting to take a look...
Thanks
--
Gustavo
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] drm/amdgpu/smu10: Replace one-element array and use struct_size() helper
2020-05-22 17:51 ` Gustavo A. R. Silva
@ 2020-05-22 17:54 ` Alex Deucher
0 siblings, 0 replies; 5+ messages in thread
From: Alex Deucher @ 2020-05-22 17:54 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Gustavo A. R. Silva, David Airlie, LKML, amd-gfx list,
Maling list - DRI developers, Alex Deucher, Evan Quan,
Christian König
On Fri, May 22, 2020 at 1:46 PM Gustavo A. R. Silva
<gustavoars@kernel.org> wrote:
>
> On Wed, May 20, 2020 at 09:42:27AM +0200, Christian König wrote:
> > >
> > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> >
> > Acked-by: Christian König <christian.koenig@amd.com>
> >
> > May I suggest that we add a section how to correctly do this to
> > Documentation/process/coding-style.rst or similar document?
> >
>
> That's already on my list. :)
>
> > I've seen a bunch of different approaches and some even doesn't work with
> > some gcc versions and result in a broken binary.
> >
>
> Do you have an example of that one that doesn't work with some GCC
> versions? It'd be interesting to take a look...
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/gpu/drm/radeon/radeon_atombios.c?id=a7ee824a6255e347ea76e2f00827e81bbe01004e
Alex
>
> Thanks
> --
> Gustavo
> _______________________________________________
> amd-gfx mailing list
> amd-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
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^ permalink raw reply [flat|nested] 5+ messages in thread
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2020-05-19 22:55 [PATCH] drm/amdgpu/smu10: Replace one-element array and use struct_size() helper Gustavo A. R. Silva
2020-05-20 7:42 ` Christian König
2020-05-20 18:17 ` Alex Deucher
2020-05-22 17:51 ` Gustavo A. R. Silva
2020-05-22 17:54 ` Alex Deucher
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