drm/nouveau: fix notifier memory corruption bug

nouveau_bo_wr32 expects offset to be in words, but we pass value in bytes,
so after commit 73412c3854c877e5f37ad944ee8977addde4d35a ("drm/nouveau: allocate
kernel's notifier object at end of block") we started to overwrite some memory
after notifier buffer object (previously m2mf_ntfy was always 0, so it didn't
matter it was a value in bytes).

Reported-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reported-by: Nigel Cunningham <lkml@nigelcunningham.com.au>
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Pekka Paalanen <pq@iki.fi>
Cc: stable@kernel.org    [2.6.38]
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
index 889c4454682e674316685ac322b55b3960610dc1..39aee6d4daf869ab5c5c931bd7174b249aab10b5 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
@@ -181,13 +181,13 @@ nouveau_fbcon_sync(struct fb_info *info)
                OUT_RING  (chan, 0);
        }
 
-       nouveau_bo_wr32(chan->notifier_bo, chan->m2mf_ntfy + 3, 0xffffffff);
+       nouveau_bo_wr32(chan->notifier_bo, chan->m2mf_ntfy/4 + 3, 0xffffffff);
        FIRE_RING(chan);
        mutex_unlock(&chan->mutex);
 
        ret = -EBUSY;
        for (i = 0; i < 100000; i++) {
-               if (!nouveau_bo_rd32(chan->notifier_bo, chan->m2mf_ntfy + 3)) {
+               if (!nouveau_bo_rd32(chan->notifier_bo, chan->m2mf_ntfy/4 + 3)) {
                        ret = 0;
                        break;
                }