drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC

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

@@ -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)
+		return -EINVAL;
+
 	obj = drm_gem_object_lookup(file, args->handle);
 	if (!obj)
 		return -ENOENT;
@@ -360,6 +363,9 @@ static int etnaviv_ioctl_wait_fence(struct drm_device *dev, void *data,
 	if (args->flags & ~(ETNA_WAIT_NONBLOCK))
 		return -EINVAL;
 
+	if (args->timeout.tv_nsec > NSEC_PER_SEC)
+		return -EINVAL;
+
 	if (args->pipe >= ETNA_MAX_PIPES)
 		return -EINVAL;
 
@@ -411,6 +417,9 @@ static int etnaviv_ioctl_gem_wait(struct drm_device *dev, void *data,
 	if (args->flags & ~(ETNA_WAIT_NONBLOCK))
 		return -EINVAL;
 
+	if (args->timeout.tv_nsec > NSEC_PER_SEC)
+		return -EINVAL;
+
 	if (args->pipe >= ETNA_MAX_PIPES)
 		return -EINVAL;