From: Doug Goldstein <cardoe@cardoe.com>
Date: Mon, 10 Mar 2014 01:20:22 +0000 (-0500)
Subject: core: don't crash if pc is past flash
X-Git-Tag: v1.2~10^2~1
X-Git-Url: https://git.htl-mechatronik.at/public/?a=commitdiff_plain;h=d9701a754e742fc3491d619fad928ac544b32b93;p=sx%2Fsimavr.git

core: don't crash if pc is past flash

If we somehow had bad code that pointed us past the end of the flash it
would segfault simavr rather than catching the bad case, this fixes and
that wraps the check in an unlikely() branch hint since its very
unlikely we will take that case.
---

diff --git a/simavr/sim/sim_core.c b/simavr/sim/sim_core.c
index 538caa4..840977a 100644
--- a/simavr/sim/sim_core.c
+++ b/simavr/sim/sim_core.c
@@ -496,6 +496,15 @@ avr_flashaddr_t avr_run_one(avr_t * avr)
 	avr->trace_data->touched[0] = avr->trace_data->touched[1] = avr->trace_data->touched[2] = 0;
 #endif
 
+	/* Ensure we don't crash simavr due to a bad instruction reading past
+	 * the end of the flash.
+	 */
+	if (unlikely(avr->pc >= avr->flashend)) {
+		STATE("CRASH\n");
+		crash(avr);
+		return 0;
+	}
+
 	uint32_t		opcode = (avr->flash[avr->pc + 1] << 8) | avr->flash[avr->pc];
 	avr_flashaddr_t	new_pc = avr->pc + 2;	// future "default" pc
 	int 			cycle = 1;