The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 17b11b76b87afe9f8be199d7a5f442497133e2b0 Mon Sep 17 00:00:00 2001
From: Boris Brezillon boris.brezillon@free-electrons.com Date: Thu, 18 Jan 2018 15:58:21 +0100 Subject: [PATCH] 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: ca26d28bbaa3 ("drm/vc4: improve throughput by pipelining binning and rendering jobs") Cc: stable@vger.kernel.org Signed-off-by: Boris Brezillon boris.brezillon@free-electrons.com Signed-off-by: Eric Anholt eric@anholt.net Reviewed-by: Eric Anholt eric@anholt.net Link: https://patchwork.freedesktop.org/patch/msgid/20180118145821.22344-1-boris.b...
diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c index e3e868cdee79..c94cce96544c 100644 --- a/drivers/gpu/drm/vc4/vc4_gem.c +++ b/drivers/gpu/drm/vc4/vc4_gem.c @@ -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])