On 12/10/2018 15:02, Chris Wilson wrote:
Handle integer overflow when computing the sub-page length for shmem
backed pread/pwrite.

Reported-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Cc: sta...@vger.kernel.org
---
  drivers/gpu/drm/i915/i915_gem.c | 12 ++----------
  1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 7d45e71100bc..93d09282710d 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1127,11 +1127,7 @@ i915_gem_shmem_pread(struct drm_i915_gem_object *obj,
        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,
@@ -1575,11 +1571,7 @@ i915_gem_shmem_pwrite(struct drm_i915_gem_object *obj,
        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,


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

Regards,

Tvrtko
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