From: Pawel Moll Date: Fri, 5 Aug 2016 14:07:10 +0000 (+0100) Subject: bus: arm-ccn: Do not attempt to configure XPs for cycle counter X-Git-Tag: v4.8-rc6~19^2~4^2~6 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=b7c1beb278e8e3dc664ed3df3fc786db126120a9;p=linux.git bus: arm-ccn: Do not attempt to configure XPs for cycle counter Fuzzing the CCN perf driver revealed a small but definitely dangerous mistake in the event setup code. When a cycle counter is requested, the driver should not reconfigure the events bus at all, otherwise it will corrupt (in most but the simplest cases) its configuration and may end up accessing XP array out of its bounds and corrupting control registers. Reported-by: Mark Rutland Reviewed-by: Mark Rutland Tested-by: Mark Rutland Cc: stable@vger.kernel.org # 3.17+ Signed-off-by: Pawel Moll --- diff --git a/drivers/bus/arm-ccn.c b/drivers/bus/arm-ccn.c index a11b9bb1f27c..9bbb0ab275e4 100644 --- a/drivers/bus/arm-ccn.c +++ b/drivers/bus/arm-ccn.c @@ -897,6 +897,10 @@ static void arm_ccn_pmu_xp_dt_config(struct perf_event *event, int enable) struct arm_ccn_component *xp; u32 val, dt_cfg; + /* Nothing to do for cycle counter */ + if (hw->idx == CCN_IDX_PMU_CYCLE_COUNTER) + return; + if (CCN_CONFIG_TYPE(event->attr.config) == CCN_TYPE_XP) xp = &ccn->xp[CCN_CONFIG_XP(event->attr.config)]; else