[2/2] drm/i915: Handle vm_mmap error during I915_GEM_MMAP ioctl with WC set
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Message ID 20190107085656.22521-2-joonas.lahtinen@linux.intel.com
State New
Headers show
Series
  • [1/2] drm/i915: Prevent a race during I915_GEM_MMAP ioctl with WC set
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Commit Message

Joonas Lahtinen Jan. 7, 2019, 8:56 a.m. UTC
Add err goto label and use it when VMA can't be established or changes
underneath.

Fixes: 1816f9236303 ("drm/i915: Support creation of unbound wc user mappings for objects")
Reported-by: Adam Zabrocki <adamza@microsoft.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: <stable@vger.kernel.org> # v4.0+
Cc: Akash Goel <akash.goel@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Adam Zabrocki <adamza@microsoft.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

Comments

Chris Wilson Jan. 7, 2019, 9:18 a.m. UTC | #1
Quoting Joonas Lahtinen (2019-01-07 08:56:56)
> Add err goto label and use it when VMA can't be established or changes
> underneath.
> 
> Fixes: 1816f9236303 ("drm/i915: Support creation of unbound wc user mappings for objects")

Dubious. All it changes is one branch where the error is forced to
-ENOMEM.

> Reported-by: Adam Zabrocki <adamza@microsoft.com>
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: <stable@vger.kernel.org> # v4.0+
> Cc: Akash Goel <akash.goel@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Adam Zabrocki <adamza@microsoft.com>
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index f1d594a53978..97cbc0e27e3e 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1738,6 +1738,9 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
>         addr = vm_mmap(obj->base.filp, 0, args->size,
>                        PROT_READ | PROT_WRITE, MAP_SHARED,
>                        args->offset);
> +       if (IS_ERR((void *)addr))
> +               goto err;
> +
>         if (args->flags & I915_MMAP_WC) {
>                 struct mm_struct *mm = current->mm;
>                 struct vm_area_struct *vma;
> @@ -1753,17 +1756,22 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
>                 else
>                         addr = -ENOMEM;
>                 up_write(&mm->mmap_sem);
> +               if (IS_ERR((void *)addr))
> +                       goto err;

The issue still remains that we are returning having called vm_mmap and
leaving the vma intact. And we've established above that calling
vm_munmap() is a race.
-Chris
Tvrtko Ursulin Jan. 7, 2019, 9:29 a.m. UTC | #2
On 07/01/2019 08:56, Joonas Lahtinen wrote:
> Add err goto label and use it when VMA can't be established or changes
> underneath.
> 
> Fixes: 1816f9236303 ("drm/i915: Support creation of unbound wc user mappings for objects")
> Reported-by: Adam Zabrocki <adamza@microsoft.com>
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: <stable@vger.kernel.org> # v4.0+
> Cc: Akash Goel <akash.goel@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Adam Zabrocki <adamza@microsoft.com>
> ---
>   drivers/gpu/drm/i915/i915_gem.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index f1d594a53978..97cbc0e27e3e 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1738,6 +1738,9 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
>   	addr = vm_mmap(obj->base.filp, 0, args->size,
>   		       PROT_READ | PROT_WRITE, MAP_SHARED,
>   		       args->offset);
> +	if (IS_ERR((void *)addr))
> +		goto err;
> +
>   	if (args->flags & I915_MMAP_WC) {
>   		struct mm_struct *mm = current->mm;
>   		struct vm_area_struct *vma;
> @@ -1753,17 +1756,22 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
>   		else
>   			addr = -ENOMEM;
>   		up_write(&mm->mmap_sem);
> +		if (IS_ERR((void *)addr))
> +			goto err;
>   
>   		/* This may race, but that's ok, it only gets set */
>   		WRITE_ONCE(obj->frontbuffer_ggtt_origin, ORIGIN_CPU);
>   	}
>   	i915_gem_object_put(obj);
> -	if (IS_ERR((void *)addr))
> -		return addr;
>   
>   	args->addr_ptr = (uint64_t) addr;
>   
>   	return 0;
> +
> +err:
> +	i915_gem_object_put(obj);
> +
> +	return addr;
>   }
>   
>   static unsigned int tile_row_pages(const struct drm_i915_gem_object *obj)
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko

Patch
diff mbox series

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index f1d594a53978..97cbc0e27e3e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1738,6 +1738,9 @@  i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
 	addr = vm_mmap(obj->base.filp, 0, args->size,
 		       PROT_READ | PROT_WRITE, MAP_SHARED,
 		       args->offset);
+	if (IS_ERR((void *)addr))
+		goto err;
+
 	if (args->flags & I915_MMAP_WC) {
 		struct mm_struct *mm = current->mm;
 		struct vm_area_struct *vma;
@@ -1753,17 +1756,22 @@  i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
 		else
 			addr = -ENOMEM;
 		up_write(&mm->mmap_sem);
+		if (IS_ERR((void *)addr))
+			goto err;
 
 		/* This may race, but that's ok, it only gets set */
 		WRITE_ONCE(obj->frontbuffer_ggtt_origin, ORIGIN_CPU);
 	}
 	i915_gem_object_put(obj);
-	if (IS_ERR((void *)addr))
-		return addr;
 
 	args->addr_ptr = (uint64_t) addr;
 
 	return 0;
+
+err:
+	i915_gem_object_put(obj);
+
+	return addr;
 }
 
 static unsigned int tile_row_pages(const struct drm_i915_gem_object *obj)