From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 14 Nov 2016 11:29:30 +0000 (+0000)
Subject: drm/i915: Don't touch NULL sg on i915_gem_object_get_pages_gtt() error
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=2420489bcb8910188578acc0c11c75445c2e4b92;p=linux-beck.git

drm/i915: Don't touch NULL sg on i915_gem_object_get_pages_gtt() error

On the DMA mapping error path, sg may be NULL (it has already been
marked as the last scatterlist entry), and we should avoid dereferencing
it again.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: e227330223a7 ("drm/i915: avoid leaking DMA mappings")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Cc: stable@vger.kernel.org
Link: http://patchwork.freedesktop.org/patch/msgid/20161114112930.2033-1-chris@chris-wilson.co.uk
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
(cherry picked from commit b17993b7b29612369270567643bcff814f4b3d7f)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 91ab7e9d6d2e..00eb4814b913 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2268,7 +2268,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 			page = shmem_read_mapping_page(mapping, i);
 			if (IS_ERR(page)) {
 				ret = PTR_ERR(page);
-				goto err_pages;
+				goto err_sg;
 			}
 		}
 #ifdef CONFIG_SWIOTLB
@@ -2311,8 +2311,9 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 
 	return 0;
 
-err_pages:
+err_sg:
 	sg_mark_end(sg);
+err_pages:
 	for_each_sgt_page(page, sgt_iter, st)
 		put_page(page);
 	sg_free_table(st);