[PATCH] tracing: use strscpy to replace strlcpy

[PATCH] tracing: use strscpy to replace strlcpy

[XueBing Chen]

The strlcpy should not be used because it doesn't limit the source
length. Preferred is strscpy.

Signed-off-by: XueBing Chen <chenxuebing@jari.cn>
---
 kernel/trace/trace_boot.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index 778200dd8ede..2bf76550bb4e 100644
--- a/kernel/trace/trace_boot.c
+++ b/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 (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) {
+		if (strscpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) {
 			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 (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) {
+		if (strscpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf)) {
 			pr_err("String is too long: %s\n", p);
 			continue;
 		}
@@ -486,7 +486,7 @@ 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 (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf))
+		if (strscpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf))
 			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);
@@ -494,7 +494,7 @@ trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode,
 
 	if (IS_ENABLED(CONFIG_HIST_TRIGGERS)) {
 		xbc_node_for_each_array_value(enode, "actions", anode, p) {
-			if (strlcpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf))
+			if (strscpy(buf, p, ARRAY_SIZE(buf)) >= ARRAY_SIZE(buf))
 				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);
-- 
2.25.1

Re: [PATCH] tracing: use strscpy to replace strlcpy

[Steven Rostedt]

On Mon, 11 Jul 2022 22:26:12 +0800 (GMT+08:00)
"XueBing Chen" <chenxuebing@jari.cn> wrote:

> The strlcpy should not be used because it doesn't limit the source
> length. Preferred is strscpy.

That's not enough justification to make the switch.

These calls are done at boot up. If there's a bug in the source, I rather
have it crash.

-- Steve


> 
> Signed-off-by: XueBing Chen <chenxuebing@jari.cn>

Re: [PATCH] tracing: use strscpy to replace strlcpy

[Steven Rostedt]

On Mon, 11 Jul 2022 10:41:25 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 11 Jul 2022 22:26:12 +0800 (GMT+08:00)
> "XueBing Chen" <chenxuebing@jari.cn> wrote:
> 
> > The strlcpy should not be used because it doesn't limit the source
> > length. Preferred is strscpy.  
> 
> That's not enough justification to make the switch.
> 
> These calls are done at boot up. If there's a bug in the source, I rather
> have it crash.

And unless there is good justification and understanding of how the code
works, blindly switching strlcpy() with strscpy() can have undesirable
consequences:

  https://lore.kernel.org/all/20220701094403.3044-1-adrian.hunter@intel.com/T/#u

Please stop changing all strlcpy() to strscpy() unless there's good
justification to do so. Just saying "strscpy() is preferred", is not
justification to make the change.

-- Steve