Re: [PATCH] dma-mapping: Add BUG_ON for uninitialized dma_ops

[Marek Szyprowski]

On 6/12/2013 5:06 PM, Arnd Bergmann wrote:
> On Tuesday 11 June 2013, James Bottomley wrote:
> > Really, no, it's not a good idea at all.  It invites tons of patches
> > littering the code with BUG_ONs where we might possibly get a NULL
> > dereference.  All it does is add extra instructions to a code path for
> > no actual benefit.
> >
> > If you can answer the question: what more information does the BUG_ON
> > give you than the NULL deref Oops would not? then it might be
> > reasonable.
>
> The question is if a user can trigger the NULL dereference intentionally,
> in which case they might get the kernel to jump into a  user-provided
> buffer.

I don't any possibility for userspace to alter the ops pointer, so if you
think that BUG_ON() approach causes additional overhead then I'm fine to
remove it.

Best regards
--
Marek Szyprowski
Samsung R&D Institute Poland


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/