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

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

[Steven Rostedt]

From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

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/20230615180420.400769-1-azeemshaikh38@gmail.com/

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 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 5fe525f1b8cc..7ccc7a8e155b 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 (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;
 		}
@@ -486,7 +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 (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);
@@ -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 (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);
-- 
2.39.2

Re: [PATCH] tracing/boot: Test strscpy() against less than zero for error

[Masami Hiramatsu]

On Tue, 4 Jul 2023 10:08:07 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
> 
> 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.

Indeed. This looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thank you,

> 
> Link: https://lore.kernel.org/linux-trace-kernel/20230615180420.400769-1-azeemshaikh38@gmail.com/
> 
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
>  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 5fe525f1b8cc..7ccc7a8e155b 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 (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;
>  		}
> @@ -486,7 +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 (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);
> @@ -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 (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);
> -- 
> 2.39.2
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>