linux-kernel - [patch] drm/vmwgfx: fix a NULL dereference

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Date:	Thu, 28 Jan 2016 12:06:46 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	David Airlie <airlied@...ux.ie>,
	Daniel Vetter <daniel.vetter@...ll.ch>
Cc:	Thomas Hellstrom <thellstrom@...are.com>,
	Alex Deucher <alexander.deucher@....com>,
	Daniel Stone <daniels@...labora.com>,
	Sinclair Yeh <syeh@...are.com>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [patch] drm/vmwgfx: fix a NULL dereference

We dereference "eaction->event" inside the call to drm_send_event_locked()
so should hold off on setting it to NULL until afterward.

Fixes: fb740cf2492c ("drm: Create drm_send_event helpers")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
index e0edf14..37c305b 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
@@ -880,8 +880,8 @@ static void vmw_event_fence_action_seq_passed(struct vmw_fence_action *action)
 	}
 
 	list_del_init(&eaction->fpriv_head);
-	eaction->event = NULL;
 	drm_send_event_locked(dev, eaction->event);
+	eaction->event = NULL;
 	spin_unlock_irqrestore(&dev->event_lock, irq_flags);
 }