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SubjectRe: [Y2038] [PATCH v2 13/24] drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC
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On Fri, 2019-12-13 at 21:53 +0100, Arnd Bergmann wrote:
> Most kernel interfaces that take a timespec require normalized
> representation with tv_nsec between 0 and NSEC_PER_SEC.
>
> Passing values larger than 0x100000000ull further behaves differently
> on 32-bit and 64-bit kernels, and can cause the latter to spend a long
> time counting seconds in timespec64_sub()/set_normalized_timespec64().
>
> Reject those large values at the user interface to enforce sane and
> portable behavior.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/gpu/drm/etnaviv/etnaviv_drv.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> index 1f9c01be40d7..95d72dc00280 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> @@ -297,6 +297,9 @@ static int etnaviv_ioctl_gem_cpu_prep(struct drm_device *dev, void *data,
> if (args->op & ~(ETNA_PREP_READ | ETNA_PREP_WRITE | ETNA_PREP_NOSYNC))
> return -EINVAL;
>
> + if (args->timeout.tv_nsec > NSEC_PER_SEC)
[...]

There's an off-by-one error between the subject line and the actual
changes. The subject line seems to have the correct comparison.

Ben.

--
Ben Hutchings, Software Developer Codethink Ltd
https://www.codethink.co.uk/ Dale House, 35 Dale Street
Manchester, M1 2HF, United Kingdom

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