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<b><a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - [skl] [drm] BUG: unable to handle kernel NULL pointer dereference at (null) [drm_kms_helper]"
href="https://bugs.freedesktop.org/show_bug.cgi?id=100727#c16">Comment # 16</a>
on <a class="bz_bug_link
bz_status_NEEDINFO "
title="NEEDINFO - [skl] [drm] BUG: unable to handle kernel NULL pointer dereference at (null) [drm_kms_helper]"
href="https://bugs.freedesktop.org/show_bug.cgi?id=100727">bug 100727</a>
from <span class="vcard"><a class="email" href="mailto:jirislaby@gmail.com" title="Jiri Slaby <jirislaby@gmail.com>"> <span class="fn">Jiri Slaby</span></a>
</span></b>
<pre>I hit it with 4.15.14 right now. I don't know how to reproduce though.
What about this (mgr->mst_primary seems to be NULL here)?
@@ -1288,7 +1288,10 @@ static struct drm_dp_mst_branch
*drm_dp_get_mst_branch_device(struct drm_dp_mst_
}
}
}
- kref_get(&mstb->kref);
+ if (WARN_ON_ONCE(!mstb))
+ ;
+ else
+ kref_get(&mstb->kref);
out:
mutex_unlock(&mgr->lock);
return mstb;</pre>
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