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Commit 17b11b76 authored by Boris Brezillon's avatar Boris Brezillon Committed by Eric Anholt
Browse files

drm/vc4: Fix NULL pointer dereference in vc4_save_hang_state() 



When saving BOs in the hang state we skip one entry of the
kernel_state->bo[] array, thus leaving it to NULL. This leads to a NULL
pointer dereference when, later in this function, we iterate over all
BOs to check their ->madv state.

Fixes: ca26d28b ("drm/vc4: improve throughput by pipelining binning and rendering jobs")
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: default avatarEric Anholt <eric@anholt.net>
Reviewed-by: default avatarEric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180118145821.22344-1-boris.brezillon@free-electrons.com
parent f61145f1

drivers/gpu/drm/vc4/vc4_gem.c

+6 −6
Original line number Diff line number Diff line
@@ -146,7 +146,7 @@ vc4_save_hang_state(struct drm_device *dev) 
	struct vc4_exec_info *exec[2];

	struct vc4_bo *bo;

	unsigned long irqflags;

	unsigned int i, j, unref_list_count, prev_idx;

	unsigned int i, j, k, unref_list_count;



	kernel_state = kcalloc(1, sizeof(*kernel_state), GFP_KERNEL);

	if (!kernel_state)
@@ -182,7 +182,7 @@ vc4_save_hang_state(struct drm_device *dev) 
		return;

	}



	prev_idx = 0;

	k = 0;

	for (i = 0; i < 2; i++) {

		if (!exec[i])

			continue;
@@ -197,7 +197,7 @@ vc4_save_hang_state(struct drm_device *dev) 
			WARN_ON(!refcount_read(&bo->usecnt));

			refcount_inc(&bo->usecnt);

			drm_gem_object_get(&exec[i]->bo[j]->base);

			kernel_state->bo[j + prev_idx] = &exec[i]->bo[j]->base;

			kernel_state->bo[k++] = &exec[i]->bo[j]->base;

		}



		list_for_each_entry(bo, &exec[i]->unref_list, unref_head) {
@@ -205,12 +205,12 @@ vc4_save_hang_state(struct drm_device *dev) 
			 * because they are naturally unpurgeable.

			 */

			drm_gem_object_get(&bo->base.base);

			kernel_state->bo[j + prev_idx] = &bo->base.base;

			j++;

			kernel_state->bo[k++] = &bo->base.base;

		}

		prev_idx = j + 1;

	}



	WARN_ON_ONCE(k != state->bo_count);



	if (exec[0])

		state->start_bin = exec[0]->ct0ca;

	if (exec[1])