Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [High] accel/rocket: out-of-bounds access on elapsed_ns[] when num_cores changes --
commit 2905630551e831e7463221f4054336a62cdc4cc3 Author: Sidong Yang <[email protected]> accel/rocket: Report per-core engine usage through fdinfo This commit adds per-core engine usage accounting for client jobs on the Rocket NPU and exposes the per-core elapsed nanoseconds and BO memory stats through fdinfo. > diff --git a/drivers/accel/rocket/rocket_drv.c > b/drivers/accel/rocket/rocket_drv.c > index 8bbbce594883e..5b81d1ecc0e49 100644 > --- a/drivers/accel/rocket/rocket_drv.c > +++ b/drivers/accel/rocket/rocket_drv.c [ ... ] > @@ -86,10 +107,19 @@ rocket_open(struct drm_device *dev, struct drm_file > *file) > } > > rocket_priv->rdev = rdev; > + > + rocket_priv->engine_usage = kzalloc_flex(*rocket_priv->engine_usage, > + elapsed_ns, rdev->num_cores); > + if (!rocket_priv->engine_usage) { > + ret = -ENOMEM; > + goto err_free; > + } > + kref_init(&rocket_priv->engine_usage->kref); > + > rocket_priv->domain = rocket_iommu_domain_create(rdev->cores[0].dev); > if (IS_ERR(rocket_priv->domain)) { > ret = PTR_ERR(rocket_priv->domain); > - goto err_free; > + goto err_put_engine_usage; > } [ ... ] > @@ -139,7 +172,29 @@ static const struct drm_ioctl_desc > rocket_drm_driver_ioctls[] = { > ROCKET_IOCTL(FINI_BO, fini_bo), > }; > > -DEFINE_DRM_ACCEL_FOPS(rocket_accel_driver_fops); > +static void rocket_show_fdinfo(struct drm_printer *p, struct drm_file *file) > +{ > + struct rocket_device *rdev = to_rocket_device(file->minor->dev); > + struct rocket_file_priv *rocket_priv = file->driver_priv; > + unsigned int core; > + > + /* > + * These are estimates: the time is taken around the whole period a job > + * occupies a core, so it also covers handling the completion interrupt > + * and, for a job made of several tasks, the gaps between them. > + */ > + for (core = 0; core < rdev->num_cores; core++) > + drm_printf(p, "drm-engine-npu%u:\t%llu ns\n", core, > + rocket_priv->engine_usage->elapsed_ns[core]); [Severity: High] Can this read or write past the end of rocket_priv->engine_usage->elapsed_ns[] if rdev->num_cores changes after rocket_open()? In rocket_probe(), the DRM device is registered via rocket_device_init() -> drm_dev_register() when the first core probes, and rdev->num_cores is then incremented one by one as each subsequent core probes: drivers/accel/rocket/rocket_drv.c:rocket_probe() { if (rdev == NULL) { /* First core probing, initialize DRM device. */ rdev = rocket_device_init(drm_dev, &rocket_drm_driver); ... } unsigned int core = rdev->num_cores; ... rdev->cores[core].index = core; rdev->num_cores++; } If userspace (for example systemd-udevd reacting to the drm_dev_register() uevent, or a client opening the device while remaining cores are still probing or deferred) calls rocket_open() before all cores have finished probing, rocket_priv->engine_usage is allocated with the smaller rdev->num_cores count at that moment. Once the remaining cores finish probing and increment rdev->num_cores, calling rocket_show_fdinfo() will iterate up to the new rdev->num_cores and read past the end of elapsed_ns[]. Similarly, if a lower-indexed core is unbound via rocket_remove(), rdev->num_cores is decremented while higher-indexed cores retain their original core->index. If a file is opened afterwards, rocket_job_handle_irq() indexing engine_usage->elapsed_ns[core->index] can also write out of bounds: drivers/accel/rocket/rocket_job.c:rocket_job_handle_irq() { ... core->in_flight_job->engine_usage->elapsed_ns[core->index] += local_clock() - core->in_flight_job->start_ns; ... } Would it make sense to record the total core count allocated for rdev->cores in rocket_device_init() (or store the allocated array length in struct rocket_engine_usage) so that the allocation size and bounds stay consistent? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=1
