perf/x86/intel: Fix memory corruption

Peter Zijlstra · KAGA-KOKO · commit ede271b05946 · 2019-03-15T12:22:51.000+01:00
Through: validate_event() x86_pmu.get_event_constraints(.idx=-1) tfa_get_event_constraints() dyn_constraint() cpuc->constraint_list[-1] is used, which is an obvious out-of-bound access. In this case, simply skip the TFA constraint code, there is no event constraint with just PMC3, therefore the code will never result in the empty set. Fixes: 400816f ("perf/x86/intel: Implement support for TSX Force Abort") Reported-by: Tony Jones <tonyj@suse.com> Reported-by: "DSouza, Nelson" <nelson.dsouza@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Tony Jones <tonyj@suse.com> Tested-by: "DSouza, Nelson" <nelson.dsouza@intel.com> Cc: eranian@google.com Cc: jolsa@redhat.com Cc: stable@kernel.org Link: https://lkml.kernel.org/r/20190314130705.441549378@infradead.org
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
@@ -3410,7 +3410,7 @@ tfa_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 	/*
 	 * Without TFA we must not use PMC3.
 	 */
-	if (!allow_tsx_force_abort && test_bit(3, c->idxmsk)) {
+	if (!allow_tsx_force_abort && test_bit(3, c->idxmsk) && idx >= 0) {
 		c = dyn_constraint(cpuc, c, idx);
 		c->idxmsk64 &= ~(1ULL << 3);
 		c->weight--;
