stack limits dynamic check - fixies

based on Akos' comments:
- dynamic rlimit stack check
- recognize [stack] map arrea and handle it properly

2 files changed, 35 insertions, 19 deletions

diff --git a/ChangeLog b/ChangeLog
index e8a6c12..2470748 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2010-09-15 Jiri Olsa <olsajiri@gmail.com>
+	* dynamic rlimit stack check
+	* recognize [stack] map arrea and handle it properly
+
 2010-09-07 Jiri Olsa <olsajiri@gmail.com>
 	* adding stack limits dynamic check
 		- based on proposal from Akos Pasztory
diff --git a/src/stack.c b/src/stack.c
index ade5ef9..f38b32c 100644
--- a/src/stack.c
+++ b/src/stack.c
@@ -11,18 +11,15 @@ static __thread void *stack_end   = NULL;
 
 static unsigned long get_stack_size(struct lt_config_audit *cfg)
 {
-	static unsigned long stack_size = 0;
-	static struct rlimit rlim;
-
-	if (stack_size)
-		return stack_size;
+	struct rlimit rlim;
 
 	if (getrlimit(RLIMIT_STACK, &rlim))
 		return 0;
 
-	PRINT_VERBOSE(cfg, 1, "stack size: %lx\n", rlim.rlim_cur);
+	PRINT_VERBOSE(cfg, 1, "stack cur size: %lx, max: %lx\n",
+			rlim.rlim_cur, rlim.rlim_max);
 
-	return stack_size = rlim.rlim_cur;
+	return rlim.rlim_cur;
 }
 
 /* find and update current stack boundaries */
@@ -32,6 +29,7 @@ static int load_stack(struct lt_config_audit *cfg, void *sp)
 	char line[128];
 	int found = 0;
 	void *start, *end;
+	unsigned long stack_size;
 
 	maps = fopen("/proc/self/maps", "r");
 	if (!maps) {
@@ -40,25 +38,39 @@ static int load_stack(struct lt_config_audit *cfg, void *sp)
 		return -1;
 	}
 
+	stack_size = get_stack_size(cfg);
+	/* XXX any sane idea what to do now ?*/
+	if (!stack_size)
+		return -1;
 
 	while (!found && fgets(line, sizeof(line), maps)) {
 
-		if (1 != sscanf(line, "%*p-%p", &end))
+		if (2 != sscanf(line, "%p-%p", &start, &end))
 			continue;
 
-		/* FIXME
-		 * what if the new stack is not GROWSDOWN?
-		 * let's get the limit via RLIMIT_STACK,
-		 * which should be ok for most cases now..
-		 *
-		 * it does not feel safe/complete, but probably better
-		 * than nothing
-		 */
-		start = end - get_stack_size(cfg);
+		PRINT_VERBOSE(cfg, 1, "line  start %p, end %p\n", start, end);
+
+		/* FIXME someone smart please figure out faster way,
+		* (somehow within the sscanf call?)
+		*
+		* Also what if the new stack is not GROWSDOWN,
+		* bounded by RLIMIT_STACK?
+		*/
+		if (strstr(line, "[stack]")) {
+			void *new_start = end - get_stack_size(cfg);
+
+			/* FIXME weird, need to investigate, looks like the stack
+			* area could grow more than the stack limit (eg for xpdf)
+			*
+			* taking the lower value for now
+			*/
+			if (new_start < start)
+				start = new_start;
+		}
 
 		found = ((start < sp) && (sp < end));
 
-		PRINT_VERBOSE(cfg, 1, "start %p, end %p, sp %p, in %d\n",
+		PRINT_VERBOSE(cfg, 1, "final start %p, end %p, sp %p, in %d\n",
 				start, end, sp, found);
 	}
 
@@ -91,7 +103,7 @@ int lt_stack_framesize(struct lt_config_audit *cfg, La_regs *regs)
 			return framesize;
 	}
 
-	/* FIXME what about stacks growing up.. arm might */
+	/* FIXME what about stacks growing up.. */
 	sp_top = sp + framesize;
 
 	if (sp_top > stack_end) {