2021-09-27 13:00:17

by Arnd Bergmann

Subject: [PATCH] drm/amdgpu: fix warning for overflow check

From: Arnd Bergmann <[email protected]>

The overflow check in amdgpu_bo_list_create() causes a warning with
clang-14 on 64-bit architectures, since the limit can never be
exceeded.

drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c:74:18: error: result of comparison of constant 256204778801521549 with expression of type 'unsigned int' is always false [-Werror,-Wtautological-constant-out-of-range-compare]
if (num_entries > (SIZE_MAX - sizeof(struct amdgpu_bo_list))
~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The check remains useful for 32-bit architectures, so just avoid the
warning by using size_t as the type for the count.

Fixes: 920990cb080a ("drm/amdgpu: allocate the bo_list array after the list")
Signed-off-by: Arnd Bergmann <[email protected]>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 2 +-
drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
index 15c45b2a3983..714178f1b6c6 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
@@ -61,7 +61,7 @@ static void amdgpu_bo_list_free(struct kref *ref)

int amdgpu_bo_list_create(struct amdgpu_device *adev, struct drm_file *filp,
struct drm_amdgpu_bo_list_entry *info,
- unsigned num_entries, struct amdgpu_bo_list **result)
+ size_t num_entries, struct amdgpu_bo_list **result)
{
unsigned last_entry = 0, first_userptr = num_entries;
struct amdgpu_bo_list_entry *array;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
index c905a4cfc173..044b41f0bfd9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
@@ -61,7 +61,7 @@ int amdgpu_bo_create_list_entry_array(struct drm_amdgpu_bo_list_in *in,
int amdgpu_bo_list_create(struct amdgpu_device *adev,
struct drm_file *filp,
struct drm_amdgpu_bo_list_entry *info,
- unsigned num_entries,
+ size_t num_entries,
struct amdgpu_bo_list **list);

static inline struct amdgpu_bo_list_entry *
--
2.29.2

2021-09-27 13:11:58

by Christian König

Subject: Re: [PATCH] drm/amdgpu: fix warning for overflow check

Am 27.09.21 um 14:58 schrieb Arnd Bergmann:
> From: Arnd Bergmann <[email protected]>
>
> The overflow check in amdgpu_bo_list_create() causes a warning with
> clang-14 on 64-bit architectures, since the limit can never be
> exceeded.
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c:74:18: error: result of comparison of constant 256204778801521549 with expression of type 'unsigned int' is always false [-Werror,-Wtautological-constant-out-of-range-compare]
> if (num_entries > (SIZE_MAX - sizeof(struct amdgpu_bo_list))
> ~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> The check remains useful for 32-bit architectures, so just avoid the
> warning by using size_t as the type for the count.
>
> Fixes: 920990cb080a ("drm/amdgpu: allocate the bo_list array after the list")
> Signed-off-by: Arnd Bergmann <[email protected]>

Reviewed-by: Christian König <[email protected]>

> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 2 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> index 15c45b2a3983..714178f1b6c6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> @@ -61,7 +61,7 @@ static void amdgpu_bo_list_free(struct kref *ref)
>
> int amdgpu_bo_list_create(struct amdgpu_device *adev, struct drm_file *filp,
> struct drm_amdgpu_bo_list_entry *info,
> - unsigned num_entries, struct amdgpu_bo_list **result)
> + size_t num_entries, struct amdgpu_bo_list **result)
> {
> unsigned last_entry = 0, first_userptr = num_entries;
> struct amdgpu_bo_list_entry *array;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
> index c905a4cfc173..044b41f0bfd9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
> @@ -61,7 +61,7 @@ int amdgpu_bo_create_list_entry_array(struct drm_amdgpu_bo_list_in *in,
> int amdgpu_bo_list_create(struct amdgpu_device *adev,
> struct drm_file *filp,
> struct drm_amdgpu_bo_list_entry *info,
> - unsigned num_entries,
> + size_t num_entries,
> struct amdgpu_bo_list **list);
>
> static inline struct amdgpu_bo_list_entry *

2021-09-27 19:22:03

by Alex Deucher

Subject: Re: [PATCH] drm/amdgpu: fix warning for overflow check

Applied. Thanks!

On Mon, Sep 27, 2021 at 9:07 AM Christian König
<[email protected]> wrote:
>
> Am 27.09.21 um 14:58 schrieb Arnd Bergmann:
> > From: Arnd Bergmann <[email protected]>
> >
> > The overflow check in amdgpu_bo_list_create() causes a warning with
> > clang-14 on 64-bit architectures, since the limit can never be
> > exceeded.
> >
> > drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c:74:18: error: result of comparison of constant 256204778801521549 with expression of type 'unsigned int' is always false [-Werror,-Wtautological-constant-out-of-range-compare]
> > if (num_entries > (SIZE_MAX - sizeof(struct amdgpu_bo_list))
> > ~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > The check remains useful for 32-bit architectures, so just avoid the
> > warning by using size_t as the type for the count.
> >
> > Fixes: 920990cb080a ("drm/amdgpu: allocate the bo_list array after the list")
> > Signed-off-by: Arnd Bergmann <[email protected]>
>
> Reviewed-by: Christian König <[email protected]>
>
> > ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 2 +-
> > drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h | 2 +-
> > 2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> > index 15c45b2a3983..714178f1b6c6 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
> > @@ -61,7 +61,7 @@ static void amdgpu_bo_list_free(struct kref *ref)
> >
> > int amdgpu_bo_list_create(struct amdgpu_device *adev, struct drm_file *filp,
> > struct drm_amdgpu_bo_list_entry *info,
> > - unsigned num_entries, struct amdgpu_bo_list **result)
> > + size_t num_entries, struct amdgpu_bo_list **result)
> > {
> > unsigned last_entry = 0, first_userptr = num_entries;
> > struct amdgpu_bo_list_entry *array;
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
> > index c905a4cfc173..044b41f0bfd9 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.h
> > @@ -61,7 +61,7 @@ int amdgpu_bo_create_list_entry_array(struct drm_amdgpu_bo_list_in *in,
> > int amdgpu_bo_list_create(struct amdgpu_device *adev,
> > struct drm_file *filp,
> > struct drm_amdgpu_bo_list_entry *info,
> > - unsigned num_entries,
> > + size_t num_entries,
> > struct amdgpu_bo_list **list);
> >
> > static inline struct amdgpu_bo_list_entry *
>