In commit a4f5ea64f0a8 ("drm/i915: Refactor object page API"), I
reordered the object->pages teardown to be more friendly wrt to a
separate obj->mm.lock. However, I overlooked the phys object and left it
with a dangling use-after-free of its phys_handle. Move the allocation
of the phys handle to get_pages and it release to put_pages to prevent
the invalid access and to improve symmetry.
v2: Add commentary about always aligning to page size.
Testcase: igt/drv_selftest/objects
Reported-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Fixes: a4f5ea64f0a8 ("drm/i915: Refactor object page API")
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 53 ++++++++++++++++++++++++++---------------
1 file changed, 34 insertions(+), 19 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index dd1a34ac830f..9794dd655877 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -176,21 +176,35 @@ static struct sg_table *
i915_gem_object_get_pages_phys(struct drm_i915_gem_object *obj)
{
struct address_space *mapping = obj->base.filp->f_mapping;
- char *vaddr = obj->phys_handle->vaddr;
+ drm_dma_handle_t *phys;
struct sg_table *st;
struct scatterlist *sg;
+ char *vaddr;
int i;
if (WARN_ON(i915_gem_object_needs_bit17_swizzle(obj)))
return ERR_PTR(-EINVAL);
+ /* Always aligning to the object size, allows a single allocation
+ * to handle all possible callers, and given typical object sizes,
+ * the alignment of the buddy allocation will naturally match.
+ */
+ phys = drm_pci_alloc(obj->base.dev,
+ obj->base.size,
+ roundup_pow_of_two(obj->base.size));
+ if (!phys)
+ return ERR_PTR(-ENOMEM);
+
+ vaddr = phys->vaddr;
for (i = 0; i < obj->base.size / PAGE_SIZE; i++) {
struct page *page;
char *src;
page = shmem_read_mapping_page(mapping, i);
- if (IS_ERR(page))
- return ERR_CAST(page);
+ if (IS_ERR(page)) {
+ st = ERR_CAST(page);
+ goto err_phys;
+ }
src = kmap_atomic(page);
memcpy(vaddr, src, PAGE_SIZE);
@@ -204,21 +218,29 @@ i915_gem_object_get_pages_phys(struct drm_i915_gem_object *obj)
i915_gem_chipset_flush(to_i915(obj->base.dev));
st = kmalloc(sizeof(*st), GFP_KERNEL);
- if (st == NULL)
- return ERR_PTR(-ENOMEM);
+ if (st == NULL) {
+ st = ERR_PTR(-ENOMEM);
+ goto err_phys;
+ }
if (sg_alloc_table(st, 1, GFP_KERNEL)) {
kfree(st);
- return ERR_PTR(-ENOMEM);
+ st = ERR_PTR(-ENOMEM);
+ goto err_phys;
}
sg = st->sgl;
sg->offset = 0;
sg->length = obj->base.size;
- sg_dma_address(sg) = obj->phys_handle->busaddr;
+ sg_dma_address(sg) = phys->busaddr;
sg_dma_len(sg) = obj->base.size;
+ obj->phys_handle = phys;
+ return st;
+
+err_phys:
+ drm_pci_free(obj->base.dev, phys);
return st;
}
@@ -274,12 +296,13 @@ i915_gem_object_put_pages_phys(struct drm_i915_gem_object *obj,
sg_free_table(pages);
kfree(pages);
+
+ drm_pci_free(obj->base.dev, obj->phys_handle);
}
static void
i915_gem_object_release_phys(struct drm_i915_gem_object *obj)
{
- drm_pci_free(obj->base.dev, obj->phys_handle);
i915_gem_object_unpin_pages(obj);
}
@@ -540,15 +563,13 @@ int
i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
int align)
{
- drm_dma_handle_t *phys;
int ret;
- if (obj->phys_handle) {
- if ((unsigned long)obj->phys_handle->vaddr & (align -1))
- return -EBUSY;
+ if (align > obj->base.size)
+ return -EINVAL;
+ if (obj->ops == &i915_gem_phys_ops)
return 0;
- }
if (obj->mm.madv != I915_MADV_WILLNEED)
return -EFAULT;
@@ -564,12 +585,6 @@ i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
if (obj->mm.pages)
return -EBUSY;
- /* create a new object */
- phys = drm_pci_alloc(obj->base.dev, obj->base.size, align);
- if (!phys)
- return -ENOMEM;
-
- obj->phys_handle = phys;
obj->ops = &i915_gem_phys_ops;
return i915_gem_object_pin_pages(obj);
--
2.11.0
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