Commit 703dd66f authored Aug 05, 2016 by Pawel Moll Committed by Sasha Levin Oct 04, 2016

bus: arm-ccn: Do not attempt to configure XPs for cycle counter



[ Upstream commit b7c1beb278e8e3dc664ed3df3fc786db126120a9 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

parent 26a0e0c2

drivers/bus/arm-ccn.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -804,6 +804,10 @@ 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