[PATCH] drm/etnaviv: limit submit sizes

[Christian Gmeiner]

Am Fr., 17. Dez. 2021 um 11:59 Uhr schrieb Lucas Stach <l.stach at pengutronix.de>:
>
> Currently we allow rediculous ammounts of kernel memory being allocated
> via the etnaviv GEM_SUBMIT ioctl, which is a pretty easy DoS vector. Put
> some reasonable limits in to fix this.
>
> The commandstream size is limited to 64KB, which was already a soft limit
> on older kernels after which the kernel only took submits on a best effort
> base, so there is no userspace that tries to submit commandstreams larger
> than this. Even if the whole commandstream is a single incrementing address
> load, the size limit also limits the number of potential relocs and
> referenced buffers to slightly under 64K, so use the same limit for those
> arguments. The performance monitoring infrastructure currently supports
> less than 50 performance counter signals, so limiting them to 128 on a
> single submit seems like a reasonably future-proof number for now. This
> number can be bumped if needed without breaking the interface.
>
> Cc: stable at vger.kernel.org
> Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
> Signed-off-by: Lucas Stach <l.stach at pengutronix.de>

Reviewed-by: Christian Gmeiner <christian.gmeiner at gmail.com>

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Christian Gmeiner, MSc

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