Re: [Intel-gfx] [PATCH v5 4/7] drm/i915: Check for integer truncation on the configuration of ttm place

2022-08-03 Thread Jani Nikula 
On Mon, 25 Jul 2022, Gwan-gyeong Mun  wrote:
> There is an impedance mismatch between the first/last valid page
> frame number of ttm place in unsigned and our memory/page accounting in
> unsigned long.
> As the object size is under the control of userspace, we have to be prudent
> and catch the conversion errors.
> To catch the implicit truncation as we switch from unsigned long to
> unsigned, we use overflows_type check and report E2BIG or overflow_type
> prior to the operation.
>
> v3: Not to change execution inside a macro. (Mauro)
> Add safe_conversion_gem_bug_on() macro and remove temporal
> SAFE_CONVERSION() macro.
>
> v4: Fix unhandled GEM_BUG_ON() macro call from safe_conversion_gem_bug_on()
>
> Signed-off-by: Gwan-gyeong Mun 
> Cc: Chris Wilson 
> Cc: Matthew Auld 
> Cc: Thomas Hellström 
> Reviewed-by: Nirmoy Das 
> Reviewed-by: Mauro Carvalho Chehab 
> Reported-by: kernel test robot 
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_ttm.c |  6 +++---
>  drivers/gpu/drm/i915/i915_gem.h |  4 
>  drivers/gpu/drm/i915/intel_region_ttm.c | 20 +---
>  3 files changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c 
> b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 9f2be1892b6c..88f2887627dc 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -140,14 +140,14 @@ i915_ttm_place_from_region(const struct 
> intel_memory_region *mr,
>   if (flags & I915_BO_ALLOC_CONTIGUOUS)
>   place->flags |= TTM_PL_FLAG_CONTIGUOUS;
>   if (offset != I915_BO_INVALID_OFFSET) {
> - place->fpfn = offset >> PAGE_SHIFT;
> - place->lpfn = place->fpfn + (size >> PAGE_SHIFT);
> + safe_conversion_gem_bug_on(&place->fpfn, offset >> PAGE_SHIFT);
> + safe_conversion_gem_bug_on(&place->lpfn, place->fpfn + (size >> 
> PAGE_SHIFT));

So the natural thing would be to have and use two orthogonal helpers, a
safe_conversion predicate and a warn:

GEM_BUG_ON(!safe_conversion(...));

or even:

if (GEM_BUG_ON(!safe_conversion(...)))
/* ... */

But GEM_BUG_ON() is surprising and does not follow the same pattern as
WARN_ON/BUG_ON. *sigh*

BR,
Jani.


>   } else if (mr->io_size && mr->io_size < mr->total) {
>   if (flags & I915_BO_ALLOC_GPU_ONLY) {
>   place->flags |= TTM_PL_FLAG_TOPDOWN;
>   } else {
>   place->fpfn = 0;
> - place->lpfn = mr->io_size >> PAGE_SHIFT;
> + safe_conversion_gem_bug_on(&place->lpfn, mr->io_size >> 
> PAGE_SHIFT);
>   }
>   }
>  }
> diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
> index 68d8d52bd541..327dacedd5d1 100644
> --- a/drivers/gpu/drm/i915/i915_gem.h
> +++ b/drivers/gpu/drm/i915/i915_gem.h
> @@ -83,5 +83,9 @@ struct drm_i915_private;
>  #endif
>  
>  #define I915_GEM_IDLE_TIMEOUT (HZ / 5)
> +#define safe_conversion_gem_bug_on(ptr, value) !({ \
> + safe_conversion(ptr, value) ? 0 \
> + : (({ GEM_BUG_ON(overflows_type(value, *ptr)); }), 1); \
> +})
>  
>  #endif /* __I915_GEM_H__ */
> diff --git a/drivers/gpu/drm/i915/intel_region_ttm.c 
> b/drivers/gpu/drm/i915/intel_region_ttm.c
> index 575d67bc6ffe..f0d143948725 100644
> --- a/drivers/gpu/drm/i915/intel_region_ttm.c
> +++ b/drivers/gpu/drm/i915/intel_region_ttm.c
> @@ -209,14 +209,26 @@ intel_region_ttm_resource_alloc(struct 
> intel_memory_region *mem,
>   if (flags & I915_BO_ALLOC_CONTIGUOUS)
>   place.flags |= TTM_PL_FLAG_CONTIGUOUS;
>   if (offset != I915_BO_INVALID_OFFSET) {
> - place.fpfn = offset >> PAGE_SHIFT;
> - place.lpfn = place.fpfn + (size >> PAGE_SHIFT);
> + if (!safe_conversion_gem_bug_on(&place.fpfn,
> + offset >> PAGE_SHIFT)) {
> + ret = -E2BIG;
> + goto out;
> + }
> + if (!safe_conversion_gem_bug_on(&place.lpfn,
> + place.fpfn + (size >> 
> PAGE_SHIFT))) {
> + ret = -E2BIG;
> + goto out;
> + }
>   } else if (mem->io_size && mem->io_size < mem->total) {
>   if (flags & I915_BO_ALLOC_GPU_ONLY) {
>   place.flags |= TTM_PL_FLAG_TOPDOWN;
>   } else {
>   place.fpfn = 0;
> - place.lpfn = mem->io_size >> PAGE_SHIFT;
> + if (!safe_conversion_gem_bug_on(&place.lpfn,
> + mem->io_size >> 
> PAGE_SHIFT)) {
> + ret = -E2BIG;
> + goto out;
> + }
>   }
>   }
>  
> @@ -224,6 +236,8 @@ intel_region_ttm_resource_alloc(struct 
> intel_memory_region *mem,
>   m

Re: [Intel-gfx] [PATCH v5 4/7] drm/i915: Check for integer truncation on the configuration of ttm place

2022-07-25 Thread Andrzej Hajda 

On 25.07.2022 11:25, Gwan-gyeong Mun wrote:

There is an impedance mismatch between the first/last valid page
frame number of ttm place in unsigned and our memory/page accounting in
unsigned long.
As the object size is under the control of userspace, we have to be prudent
and catch the conversion errors.
To catch the implicit truncation as we switch from unsigned long to
unsigned, we use overflows_type check and report E2BIG or overflow_type
prior to the operation.

v3: Not to change execution inside a macro. (Mauro)
 Add safe_conversion_gem_bug_on() macro and remove temporal
 SAFE_CONVERSION() macro.

v4: Fix unhandled GEM_BUG_ON() macro call from safe_conversion_gem_bug_on()

Signed-off-by: Gwan-gyeong Mun 
Cc: Chris Wilson 
Cc: Matthew Auld 
Cc: Thomas Hellström 
Reviewed-by: Nirmoy Das 
Reviewed-by: Mauro Carvalho Chehab 
Reported-by: kernel test robot 


Reviewed-by: Andrzej Hajda 

Regards
Andrzej

[Intel-gfx] [PATCH v5 4/7] drm/i915: Check for integer truncation on the configuration of ttm place

2022-07-25 Thread Gwan-gyeong Mun 
There is an impedance mismatch between the first/last valid page
frame number of ttm place in unsigned and our memory/page accounting in
unsigned long.
As the object size is under the control of userspace, we have to be prudent
and catch the conversion errors.
To catch the implicit truncation as we switch from unsigned long to
unsigned, we use overflows_type check and report E2BIG or overflow_type
prior to the operation.

v3: Not to change execution inside a macro. (Mauro)
Add safe_conversion_gem_bug_on() macro and remove temporal
SAFE_CONVERSION() macro.

v4: Fix unhandled GEM_BUG_ON() macro call from safe_conversion_gem_bug_on()

Signed-off-by: Gwan-gyeong Mun 
Cc: Chris Wilson 
Cc: Matthew Auld 
Cc: Thomas Hellström 
Reviewed-by: Nirmoy Das 
Reviewed-by: Mauro Carvalho Chehab 
Reported-by: kernel test robot 
---
 drivers/gpu/drm/i915/gem/i915_gem_ttm.c |  6 +++---
 drivers/gpu/drm/i915/i915_gem.h |  4 
 drivers/gpu/drm/i915/intel_region_ttm.c | 20 +---
 3 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c 
b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 9f2be1892b6c..88f2887627dc 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -140,14 +140,14 @@ i915_ttm_place_from_region(const struct 
intel_memory_region *mr,
if (flags & I915_BO_ALLOC_CONTIGUOUS)
place->flags |= TTM_PL_FLAG_CONTIGUOUS;
if (offset != I915_BO_INVALID_OFFSET) {
-   place->fpfn = offset >> PAGE_SHIFT;
-   place->lpfn = place->fpfn + (size >> PAGE_SHIFT);
+   safe_conversion_gem_bug_on(&place->fpfn, offset >> PAGE_SHIFT);
+   safe_conversion_gem_bug_on(&place->lpfn, place->fpfn + (size >> 
PAGE_SHIFT));
} else if (mr->io_size && mr->io_size < mr->total) {
if (flags & I915_BO_ALLOC_GPU_ONLY) {
place->flags |= TTM_PL_FLAG_TOPDOWN;
} else {
place->fpfn = 0;
-   place->lpfn = mr->io_size >> PAGE_SHIFT;
+   safe_conversion_gem_bug_on(&place->lpfn, mr->io_size >> 
PAGE_SHIFT);
}
}
 }
diff --git a/drivers/gpu/drm/i915/i915_gem.h b/drivers/gpu/drm/i915/i915_gem.h
index 68d8d52bd541..327dacedd5d1 100644
--- a/drivers/gpu/drm/i915/i915_gem.h
+++ b/drivers/gpu/drm/i915/i915_gem.h
@@ -83,5 +83,9 @@ struct drm_i915_private;
 #endif
 
 #define I915_GEM_IDLE_TIMEOUT (HZ / 5)
+#define safe_conversion_gem_bug_on(ptr, value) !({ \
+   safe_conversion(ptr, value) ? 0 \
+   : (({ GEM_BUG_ON(overflows_type(value, *ptr)); }), 1); \
+})
 
 #endif /* __I915_GEM_H__ */
diff --git a/drivers/gpu/drm/i915/intel_region_ttm.c 
b/drivers/gpu/drm/i915/intel_region_ttm.c
index 575d67bc6ffe..f0d143948725 100644
--- a/drivers/gpu/drm/i915/intel_region_ttm.c
+++ b/drivers/gpu/drm/i915/intel_region_ttm.c
@@ -209,14 +209,26 @@ intel_region_ttm_resource_alloc(struct 
intel_memory_region *mem,
if (flags & I915_BO_ALLOC_CONTIGUOUS)
place.flags |= TTM_PL_FLAG_CONTIGUOUS;
if (offset != I915_BO_INVALID_OFFSET) {
-   place.fpfn = offset >> PAGE_SHIFT;
-   place.lpfn = place.fpfn + (size >> PAGE_SHIFT);
+   if (!safe_conversion_gem_bug_on(&place.fpfn,
+   offset >> PAGE_SHIFT)) {
+   ret = -E2BIG;
+   goto out;
+   }
+   if (!safe_conversion_gem_bug_on(&place.lpfn,
+   place.fpfn + (size >> 
PAGE_SHIFT))) {
+   ret = -E2BIG;
+   goto out;
+   }
} else if (mem->io_size && mem->io_size < mem->total) {
if (flags & I915_BO_ALLOC_GPU_ONLY) {
place.flags |= TTM_PL_FLAG_TOPDOWN;
} else {
place.fpfn = 0;
-   place.lpfn = mem->io_size >> PAGE_SHIFT;
+   if (!safe_conversion_gem_bug_on(&place.lpfn,
+   mem->io_size >> 
PAGE_SHIFT)) {
+   ret = -E2BIG;
+   goto out;
+   }
}
}
 
@@ -224,6 +236,8 @@ intel_region_ttm_resource_alloc(struct intel_memory_region 
*mem,
mock_bo.bdev = &mem->i915->bdev;
 
ret = man->func->alloc(man, &mock_bo, &place, &res);
+
+out:
if (ret == -ENOSPC)
ret = -ENXIO;
if (!ret)
-- 
2.34.1