Commit b7c1beb2 authored Aug 05, 2016 by Pawel Moll

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 <mark.rutland@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Cc: stable@vger.kernel.org # 3.17+
Signed-off-by: Pawel Moll <pawel.moll@arm.com>

parent 4e486cba

drivers/bus/arm-ccn.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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