fbdev: Fixing arbitrary kernel leak in case FBIOGETCMAP_SPARC in sbusfb_ioctl_helper().

[mirror_ubuntu-bionic-kernel.git] / drivers / perf / arm_spe_pmu.c

diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
index 8ce262fc256133a22f6e698d4cb40e94a1f2b91d..51b40aecb7768825c7422f02a7bf6a07d4351601 100644 (file)
--- a/drivers/perf/arm_spe_pmu.c
+++ b/drivers/perf/arm_spe_pmu.c
@@ -1164,6 +1164,15 @@ static int arm_spe_pmu_device_dt_probe(struct platform_device *pdev)
        struct arm_spe_pmu *spe_pmu;
        struct device *dev = &pdev->dev;
 
+       /*
+        * If kernelspace is unmapped when running at EL0, then the SPE
+        * buffer will fault and prematurely terminate the AUX session.
+        */
+       if (arm64_kernel_unmapped_at_el0()) {
+               dev_warn_once(dev, "profiling buffer inaccessible. Try passing \"kpti=off\" on the kernel command line\n");
+               return -EPERM;
+       }
+
        spe_pmu = devm_kzalloc(dev, sizeof(*spe_pmu), GFP_KERNEL);
        if (!spe_pmu) {
                dev_err(dev, "failed to allocate spe_pmu\n");