1 files changed, 53 insertions, 29 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 77e68efbd43e..14e160a5b905 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -265,8 +265,7 @@ static bool test_field(const char *fmt, struct trace_event_call *call)
 	len = p - fmt;
 
 	for (; field->type; field++) {
-		if (strncmp(field->name, fmt, len) ||
-		    field->name[len])
+		if (strncmp(field->name, fmt, len) || field->name[len])
 			continue;
 		array_descriptor = strchr(field->type, '[');
 		/* This is an array and is OK to dereference. */
@@ -275,6 +274,32 @@ static bool test_field(const char *fmt, struct trace_event_call *call)
 	return false;
 }
 
+/* Return true if the argument pointer is safe */
+static bool process_pointer(const char *fmt, int len, struct trace_event_call *call)
+{
+	const char *r, *e, *a;
+
+	e = fmt + len;
+
+	/* Find the REC-> in the argument */
+	r = strstr(fmt, "REC->");
+	if (r && r < e) {
+		/*
+		 * Addresses of events on the buffer, or an array on the buffer is
+		 * OK to dereference. There's ways to fool this, but
+		 * this is to catch common mistakes, not malicious code.
+		 */
+		a = strchr(fmt, '&');
+		if ((a && (a < r)) || test_field(r, call))
+			return true;
+	} else if ((r = strstr(fmt, "__get_dynamic_array(")) && r < e) {
+		return true;
+	} else if ((r = strstr(fmt, "__get_sockaddr(")) && r < e) {
+		return true;
+	}
+	return false;
+}
+
 /*
  * Examine the print fmt of the event looking for unsafe dereference
  * pointers using %p* that could be recorded in the trace event and
@@ -285,12 +310,12 @@ static void test_event_printk(struct trace_event_call *call)
 {
 	u64 dereference_flags = 0;
 	bool first = true;
-	const char *fmt, *c, *r, *a;
+	const char *fmt;
 	int parens = 0;
 	char in_quote = 0;
 	int start_arg = 0;
 	int arg = 0;
-	int i;
+	int i, e;
 
 	fmt = call->print_fmt;
 
@@ -403,42 +428,41 @@ static void test_event_printk(struct trace_event_call *call)
 		case ',':
 			if (in_quote || parens)
 				continue;
+			e = i;
 			i++;
 			while (isspace(fmt[i]))
 				i++;
-			start_arg = i;
-			if (!(dereference_flags & (1ULL << arg)))
-				goto next_arg;
 
-			/* Find the REC-> in the argument */
-			c = strchr(fmt + i, ',');
-			r = strstr(fmt + i, "REC->");
-			if (r && (!c || r < c)) {
-				/*
-				 * Addresses of events on the buffer,
-				 * or an array on the buffer is
-				 * OK to dereference.
-				 * There's ways to fool this, but
-				 * this is to catch common mistakes,
-				 * not malicious code.
-				 */
-				a = strchr(fmt + i, '&');
-				if ((a && (a < r)) || test_field(r, call))
+			/*
+			 * If start_arg is zero, then this is the start of the
+			 * first argument. The processing of the argument happens
+			 * when the end of the argument is found, as it needs to
+			 * handle paranthesis and such.
+			 */
+			if (!start_arg) {
+				start_arg = i;
+				/* Balance out the i++ in the for loop */
+				i--;
+				continue;
+			}
+
+			if (dereference_flags & (1ULL << arg)) {
+				if (process_pointer(fmt + start_arg, e - start_arg, call))
 					dereference_flags &= ~(1ULL << arg);
-			} else if ((r = strstr(fmt + i, "__get_dynamic_array(")) &&
-				   (!c || r < c)) {
-				dereference_flags &= ~(1ULL << arg);
-			} else if ((r = strstr(fmt + i, "__get_sockaddr(")) &&
-				   (!c || r < c)) {
-				dereference_flags &= ~(1ULL << arg);
 			}
 
-		next_arg:
-			i--;
+			start_arg = i;
 			arg++;
+			/* Balance out the i++ in the for loop */
+			i--;
 		}
 	}
 
+	if (dereference_flags & (1ULL << arg)) {
+		if (process_pointer(fmt + start_arg, i - start_arg, call))
+			dereference_flags &= ~(1ULL << arg);
+	}
+
 	/*
 	 * If you triggered the below warning, the trace event reported
 	 * uses an unsafe dereference pointer %p*. As the data stored