Messages in this thread | | | Subject | Re: [PATCH] kptr_restrict for hiding kernel pointers from unprivileged users | From | Peter Zijlstra <> | Date | Fri, 10 Dec 2010 17:05:32 +0100 |
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On Thu, 2010-12-09 at 04:23 +0100, Eric Dumazet wrote: > > + if (kptr_restrict) { > > + if (in_interrupt()) > > + WARN(1, "%%pK used in interrupt context.\n"); > > So caller can not block BH ? > > This seems wrong to me, please consider : > > normal process context : > > spin_lock_bh() ... > > for (...) > {xxx}printf( ... "%pK" ...) > > spin_unlock_bh();
That's a bug in in_interrupt(), one I've been pointing out for a long while. Luckily we recently grew the infrastructure to deal with it.
If you write it as: if (in_irq() || in_serving_softirq() || in_nmi()) you'll not trigger for the above example.
Ideally in_serving_softirq() wouldn't exist and in_softirq() would do what in_server_softirq() does -- which would make it symmetric with the hardirq functions -- but nobody has found time to audit all in_softirq() users.
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