tracing/boot: Test strscpy() against less than zero for error

Instead of checking for -E2BIG, it is better to just check for less than
zero of strscpy() for error. Testing for -E2BIG is not very robust, and
the calling code does not really care about the error code, just that
there was an error.

One of the updates to convert strlcpy() to strscpy() had a v2 version
that changed the test from testing against -E2BIG to less than zero, but I
took the v1 version that still tested for -E2BIG.

Link: https://lore.kernel.org/linux-trace-kernel/[email protected]/
Link: https://lore.kernel.org/linux-trace-kernel/[email protected]

Cc: Mark Rutland <[email protected]>
Cc: Azeem Shaikh <[email protected]>
Cc: Kees Cook <[email protected]>
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: rostedt

kernel/trace/trace_boot.c

@@ -31,7 +31,7 @@ trace_boot_set_instance_options(struct trace_array *tr, struct xbc_node *node)
 
 	/* Common ftrace options */
 	xbc_node_for_each_array_value(node, "options", anode, p) {
-		if (strscpy(buf, p, ARRAY_SIZE(buf)) == -E2BIG) {
+		if (strscpy(buf, p, ARRAY_SIZE(buf)) < 0) {
 			pr_err("String is too long: %s\n", p);
 			continue;
 		}
@@ -87,7 +87,7 @@ trace_boot_enable_events(struct trace_array *tr, struct xbc_node *node)
 	const char *p;
 
 	xbc_node_for_each_array_value(node, "events", anode, p) {
-		if (strscpy(buf, p, ARRAY_SIZE(buf)) == -E2BIG) {
+		if (strscpy(buf, p, ARRAY_SIZE(buf)) < 0) {
 			pr_err("String is too long: %s\n", p);
 			continue;
 		}
@@ -486,15 +486,15 @@ trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode,
 
 	p = xbc_node_find_value(enode, "filter", NULL);
 	if (p && *p != '\0') {
-		if (strscpy(buf, p, ARRAY_SIZE(buf)) == -E2BIG)
+		if (strscpy(buf, p, ARRAY_SIZE(buf)) < 0)
 			pr_err("filter string is too long: %s\n", p);
 		else if (apply_event_filter(file, buf) < 0)
 			pr_err("Failed to apply filter: %s\n", buf);
 	}
 
 	if (IS_ENABLED(CONFIG_HIST_TRIGGERS)) {
 		xbc_node_for_each_array_value(enode, "actions", anode, p) {
-			if (strscpy(buf, p, ARRAY_SIZE(buf)) == -E2BIG)
+			if (strscpy(buf, p, ARRAY_SIZE(buf)) < 0)
 				pr_err("action string is too long: %s\n", p);
 			else if (trigger_process_regex(file, buf) < 0)
 				pr_err("Failed to apply an action: %s\n", p);