[PATCH 4.19 189/205] drm/i915: Large page offsets for pread/pwrite

Greg Kroah-Hartman
2018-11-19T16:39:22Z

From: Chris Wilson <chris@chris-wilson.co.uk>

commit ab0d6a141843e0b4b2709dfd37b53468b5452c3a upstream.

Handle integer overflow when computing the sub-page length for shmem
backed pread/pwrite.

Reported-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181012140228.29783-1-chris@chris-wilson.co.uk
(cherry picked from commit a5e856a5348f6cd50889d125c40bbeec7328e466)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/i915/i915_gem.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)

--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1122,11 +1122,7 @@ i915_gem_shmem_pread(struct drm_i915_gem
offset = offset_in_page(args->offset);
for (idx = args->offset >> PAGE_SHIFT; remain; idx++) {
struct page *page = i915_gem_object_get_page(obj, idx);
- int length;
-
- length = remain;
- if (offset + length > PAGE_SIZE)
- length = PAGE_SIZE - offset;
+ unsigned int length = min_t(u64, remain, PAGE_SIZE - offset);

ret = shmem_pread(page, offset, length, user_data,
page_to_phys(page) & obj_do_bit17_swizzling,
@@ -1570,11 +1566,7 @@ i915_gem_shmem_pwrite(struct drm_i915_ge
offset = offset_in_page(args->offset);
for (idx = args->offset >> PAGE_SHIFT; remain; idx++) {
struct page *page = i915_gem_object_get_page(obj, idx);
- int length;
-
- length = remain;
- if (offset + length > PAGE_SIZE)
- length = PAGE_SIZE - offset;
+ unsigned int length = min_t(u64, remain, PAGE_SIZE - offset);

ret = shmem_pwrite(page, offset, length, user_data,
page_to_phys(page) & obj_do_bit17_swizzling,