tracing: Replace all non-returning strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

No return values were used, so direct replacement with strlcpy is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] KSPP#89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230516143956.1367827-1-azeemshaikh38@gmail.com

Author: azeemshaikh38

kernel/trace/trace.c

@@ -196,7 +196,7 @@ static int boot_snapshot_index;
 
 static int __init set_cmdline_ftrace(char *str)
 {
-	strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
+	strscpy(bootup_tracer_buf, str, MAX_TRACER_SIZE);
 	default_bootup_tracer = bootup_tracer_buf;
 	/* We are using ftrace early, expand it */
 	ring_buffer_expanded = true;
@@ -281,7 +281,7 @@ static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata;
 
 static int __init set_trace_boot_options(char *str)
 {
-	strlcpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
+	strscpy(trace_boot_options_buf, str, MAX_TRACER_SIZE);
 	return 1;
 }
 __setup("trace_options=", set_trace_boot_options);
@@ -291,7 +291,7 @@ static char *trace_boot_clock __initdata;
 
 static int __init set_trace_boot_clock(char *str)
 {
-	strlcpy(trace_boot_clock_buf, str, MAX_TRACER_SIZE);
+	strscpy(trace_boot_clock_buf, str, MAX_TRACER_SIZE);
 	trace_boot_clock = trace_boot_clock_buf;
 	return 1;
 }
@@ -2521,7 +2521,7 @@ static void __trace_find_cmdline(int pid, char comm[])
 	if (map != NO_CMDLINE_MAP) {
 		tpid = savedcmd->map_cmdline_to_pid[map];
 		if (tpid == pid) {
-			strlcpy(comm, get_saved_cmdlines(map), TASK_COMM_LEN);
+			strscpy(comm, get_saved_cmdlines(map), TASK_COMM_LEN);
 			return;
 		}
 	}

kernel/trace/trace_events.c

@@ -2831,7 +2831,7 @@ static __init int setup_trace_triggers(char *str)
 	char *buf;
 	int i;
 
-	strlcpy(bootup_trigger_buf, str, COMMAND_LINE_SIZE);
+	strscpy(bootup_trigger_buf, str, COMMAND_LINE_SIZE);
 	ring_buffer_expanded = true;
 	disable_tracing_selftest("running event triggers");
 
@@ -3621,7 +3621,7 @@ static char bootup_event_buf[COMMAND_LINE_SIZE] __initdata;
 
 static __init int setup_trace_event(char *str)
 {
-	strlcpy(bootup_event_buf, str, COMMAND_LINE_SIZE);
+	strscpy(bootup_event_buf, str, COMMAND_LINE_SIZE);
 	ring_buffer_expanded = true;
 	disable_tracing_selftest("running event tracing");
 

kernel/trace/trace_events_inject.c

@@ -217,7 +217,7 @@ static int parse_entry(char *str, struct trace_event_call *call, void **pentry)
 			char *addr = (char *)(unsigned long) val;
 
 			if (field->filter_type == FILTER_STATIC_STRING) {
-				strlcpy(entry + field->offset, addr, field->size);
+				strscpy(entry + field->offset, addr, field->size);
 			} else if (field->filter_type == FILTER_DYN_STRING ||
 				   field->filter_type == FILTER_RDYN_STRING) {
 				int str_len = strlen(addr) + 1;
@@ -232,7 +232,7 @@ static int parse_entry(char *str, struct trace_event_call *call, void **pentry)
 				}
 				entry = *pentry;
 
-				strlcpy(entry + (entry_size - str_len), addr, str_len);
+				strscpy(entry + (entry_size - str_len), addr, str_len);
 				str_item = (u32 *)(entry + field->offset);
 				if (field->filter_type == FILTER_RDYN_STRING)
 					str_loc -= field->offset + field->size;

kernel/trace/trace_kprobe.c

@@ -30,7 +30,7 @@ static char kprobe_boot_events_buf[COMMAND_LINE_SIZE] __initdata;
 
 static int __init set_kprobe_boot_events(char *str)
 {
-	strlcpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE);
+	strscpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE);
 	disable_tracing_selftest("running kprobe events");
 
 	return 1;

kernel/trace/trace_probe.c

@@ -254,7 +254,7 @@ int traceprobe_parse_event_name(const char **pevent, const char **pgroup,
 			trace_probe_log_err(offset, GROUP_TOO_LONG);
 			return -EINVAL;
 		}
-		strlcpy(buf, event, slash - event + 1);
+		strscpy(buf, event, slash - event + 1);
 		if (!is_good_system_name(buf)) {
 			trace_probe_log_err(offset, BAD_GROUP_NAME);
 			return -EINVAL;