[PATCH] kernel: move from strlcpy with unused retval to strscpy

[PATCH] kernel: move from strlcpy with unused retval to strscpy

[Wolfram Sang]

Follow the advice of the below link and prefer 'strscpy' in this
subsystem. Conversion is 1:1 because the return value is not used.
Generated by a coccinelle script.

Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 kernel/acct.c                         |  2 +-
 kernel/bpf/preload/bpf_preload_kern.c |  4 ++--
 kernel/cgroup/cgroup-v1.c             |  4 ++--
 kernel/events/core.c                  |  6 +++---
 kernel/kallsyms.c                     |  4 ++--
 kernel/params.c                       |  2 +-
 kernel/printk/printk.c                |  2 +-
 kernel/relay.c                        |  4 ++--
 kernel/time/clocksource.c             |  2 +-
 kernel/trace/ftrace.c                 | 18 +++++++++---------
 kernel/trace/trace.c                  |  8 ++++----
 kernel/trace/trace_events.c           |  2 +-
 kernel/trace/trace_events_inject.c    |  4 ++--
 kernel/trace/trace_kprobe.c           |  2 +-
 kernel/trace/trace_probe.c            |  2 +-
 15 files changed, 33 insertions(+), 33 deletions(-)

diff --git a/kernel/acct.c b/kernel/acct.c
index 13706356ec54..5ee0b37acf0c 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -443,7 +443,7 @@ static void fill_ac(acct_t *ac)
 	memset(ac, 0, sizeof(acct_t));
 
 	ac->ac_version = ACCT_VERSION | ACCT_BYTEORDER;
-	strlcpy(ac->ac_comm, current->comm, sizeof(ac->ac_comm));
+	strscpy(ac->ac_comm, current->comm, sizeof(ac->ac_comm));
 
 	/* calculate run_time in nsec*/
 	run_time = ktime_get_ns();
diff --git a/kernel/bpf/preload/bpf_preload_kern.c b/kernel/bpf/preload/bpf_preload_kern.c
index 5106b5372f0c..af8dd3a7c928 100644
--- a/kernel/bpf/preload/bpf_preload_kern.c
+++ b/kernel/bpf/preload/bpf_preload_kern.c
@@ -19,9 +19,9 @@ static void free_links_and_skel(void)
 
 static int preload(struct bpf_preload_info *obj)
 {
-	strlcpy(obj[0].link_name, "maps.debug", sizeof(obj[0].link_name));
+	strscpy(obj[0].link_name, "maps.debug", sizeof(obj[0].link_name));
 	obj[0].link = maps_link;
-	strlcpy(obj[1].link_name, "progs.debug", sizeof(obj[1].link_name));
+	strscpy(obj[1].link_name, "progs.debug", sizeof(obj[1].link_name));
 	obj[1].link = progs_link;
 	return 0;
 }
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 2ade21b54dc4..ce8bcd2d014a 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -563,7 +563,7 @@ static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
 	if (!cgrp)
 		return -ENODEV;
 	spin_lock(&release_agent_path_lock);
-	strlcpy(cgrp->root->release_agent_path, strstrip(buf),
+	strscpy(cgrp->root->release_agent_path, strstrip(buf),
 		sizeof(cgrp->root->release_agent_path));
 	spin_unlock(&release_agent_path_lock);
 	cgroup_kn_unlock(of->kn);
@@ -797,7 +797,7 @@ void cgroup1_release_agent(struct work_struct *work)
 		goto out_free;
 
 	spin_lock(&release_agent_path_lock);
-	strlcpy(agentbuf, cgrp->root->release_agent_path, PATH_MAX);
+	strscpy(agentbuf, cgrp->root->release_agent_path, PATH_MAX);
 	spin_unlock(&release_agent_path_lock);
 	if (!agentbuf[0])
 		goto out_free;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2621fd24ad26..7c785b64fa3d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7954,7 +7954,7 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
 	unsigned int size;
 
 	memset(comm, 0, sizeof(comm));
-	strlcpy(comm, comm_event->task->comm, sizeof(comm));
+	strscpy(comm, comm_event->task->comm, sizeof(comm));
 	size = ALIGN(strlen(comm)+1, sizeof(u64));
 
 	comm_event->comm = comm;
@@ -8409,7 +8409,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
 	}
 
 cpy_name:
-	strlcpy(tmp, name, sizeof(tmp));
+	strscpy(tmp, name, sizeof(tmp));
 	name = tmp;
 got_name:
 	/*
@@ -8838,7 +8838,7 @@ void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len, bool unregister,
 	    ksym_type == PERF_RECORD_KSYMBOL_TYPE_UNKNOWN)
 		goto err;
 
-	strlcpy(name, sym, KSYM_NAME_LEN);
+	strscpy(name, sym, KSYM_NAME_LEN);
 	name_len = strlen(name) + 1;
 	while (!IS_ALIGNED(name_len, sizeof(u64)))
 		name[name_len++] = '\0';
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 3e7e2c2ad2f7..9a204432bf87 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -624,7 +624,7 @@ static int get_ksymbol_bpf(struct kallsym_iter *iter)
 {
 	int ret;
 
-	strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
+	strscpy(iter->module_name, "bpf", MODULE_NAME_LEN);
 	iter->exported = 0;
 	ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
 			      &iter->value, &iter->type,
@@ -644,7 +644,7 @@ static int get_ksymbol_bpf(struct kallsym_iter *iter)
  */
 static int get_ksymbol_kprobe(struct kallsym_iter *iter)
 {
-	strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
+	strscpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
 	iter->exported = 0;
 	return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
 				  &iter->value, &iter->type,
diff --git a/kernel/params.c b/kernel/params.c
index 5b92310425c5..ee2e3b674dd0 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -846,7 +846,7 @@ static void __init param_sysfs_builtin(void)
 			name_len = 0;
 		} else {
 			name_len = dot - kp->name + 1;
-			strlcpy(modname, kp->name, name_len);
+			strscpy(modname, kp->name, name_len);
 		}
 		kernel_add_sysfs_param(modname, kp, name_len);
 	}
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index a1a81fd9889b..7b1ba087b629 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2392,7 +2392,7 @@ static int __add_preferred_console(char *name, int idx, char *options,
 		return -E2BIG;
 	if (!brl_options)
 		preferred_console = i;
-	strlcpy(c->name, name, sizeof(c->name));
+	strscpy(c->name, name, sizeof(c->name));
 	c->options = options;
 	set_user_specified(c, user_specified);
 	braille_set_options(c, brl_options);
diff --git a/kernel/relay.c b/kernel/relay.c
index 6a611e779e95..e75bc76c8bfa 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -510,7 +510,7 @@ struct rchan *relay_open(const char *base_filename,
 	chan->private_data = private_data;
 	if (base_filename) {
 		chan->has_base_filename = 1;
-		strlcpy(chan->base_filename, base_filename, NAME_MAX);
+		strscpy(chan->base_filename, base_filename, NAME_MAX);
 	}
 	chan->cb = cb;
 	kref_init(&chan->kref);
@@ -581,7 +581,7 @@ int relay_late_setup_files(struct rchan *chan,
 	if (!chan || !base_filename)
 		return -EINVAL;
 
-	strlcpy(chan->base_filename, base_filename, NAME_MAX);
+	strscpy(chan->base_filename, base_filename, NAME_MAX);
 
 	mutex_lock(&relay_channels_mutex);
 	/* Is chan already set up? */
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index cee5da1e54c4..dc95af1fc8cd 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -1450,7 +1450,7 @@ static int __init boot_override_clocksource(char* str)
 {
 	mutex_lock(&clocksource_mutex);
 	if (str)
-		strlcpy(override_name, str, sizeof(override_name));
+		strscpy(override_name, str, sizeof(override_name));
 	mutex_unlock(&clocksource_mutex);
 	return 1;
 }
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index bc921a3f7ea8..654cd8ca46b9 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5991,7 +5991,7 @@ bool ftrace_filter_param __initdata;
 static int __init set_ftrace_notrace(char *str)
 {
 	ftrace_filter_param = true;
-	strlcpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
+	strscpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
 	return 1;
 }
 __setup("ftrace_notrace=", set_ftrace_notrace);
@@ -5999,7 +5999,7 @@ __setup("ftrace_notrace=", set_ftrace_notrace);
 static int __init set_ftrace_filter(char *str)
 {
 	ftrace_filter_param = true;
-	strlcpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
+	strscpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
 	return 1;
 }
 __setup("ftrace_filter=", set_ftrace_filter);
@@ -6011,14 +6011,14 @@ static int ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer);
 
 static int __init set_graph_function(char *str)
 {
-	strlcpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE);
+	strscpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE);
 	return 1;
 }
 __setup("ftrace_graph_filter=", set_graph_function);
 
 static int __init set_graph_notrace_function(char *str)
 {
-	strlcpy(ftrace_graph_notrace_buf, str, FTRACE_FILTER_SIZE);
+	strscpy(ftrace_graph_notrace_buf, str, FTRACE_FILTER_SIZE);
 	return 1;
 }
 __setup("ftrace_graph_notrace=", set_graph_notrace_function);
@@ -6803,8 +6803,8 @@ static int ftrace_get_trampoline_kallsym(unsigned int symnum,
 			continue;
 		*value = op->trampoline;
 		*type = 't';
-		strlcpy(name, FTRACE_TRAMPOLINE_SYM, KSYM_NAME_LEN);
-		strlcpy(module_name, FTRACE_TRAMPOLINE_MOD, MODULE_NAME_LEN);
+		strscpy(name, FTRACE_TRAMPOLINE_SYM, KSYM_NAME_LEN);
+		strscpy(module_name, FTRACE_TRAMPOLINE_MOD, MODULE_NAME_LEN);
 		*exported = 0;
 		return 0;
 	}
@@ -7135,7 +7135,7 @@ ftrace_func_address_lookup(struct ftrace_mod_map *mod_map,
 		if (off)
 			*off = addr - found_func->ip;
 		if (sym)
-			strlcpy(sym, found_func->name, KSYM_NAME_LEN);
+			strscpy(sym, found_func->name, KSYM_NAME_LEN);
 
 		return found_func->name;
 	}
@@ -7189,8 +7189,8 @@ int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *value,
 
 			*value = mod_func->ip;
 			*type = 'T';
-			strlcpy(name, mod_func->name, KSYM_NAME_LEN);
-			strlcpy(module_name, mod_map->mod->name, MODULE_NAME_LEN);
+			strscpy(name, mod_func->name, KSYM_NAME_LEN);
+			strscpy(module_name, mod_map->mod->name, MODULE_NAME_LEN);
 			*exported = 1;
 			preempt_enable();
 			return 0;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d3005279165d..98ce29d78110 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -189,7 +189,7 @@ static bool snapshot_at_boot;
 
 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;
@@ -244,7 +244,7 @@ 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);
@@ -254,7 +254,7 @@ 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;
 }
@@ -2452,7 +2452,7 @@ 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;
 		}
 	}
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 181f08186d32..c2e65c646980 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -3531,7 +3531,7 @@ 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");
 
diff --git a/kernel/trace/trace_events_inject.c b/kernel/trace/trace_events_inject.c
index d6b4935a78c0..abe805d471eb 100644
--- a/kernel/trace/trace_events_inject.c
+++ b/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;
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 23f7f0ec4f4c..0f0262edb48a 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -29,7 +29,7 @@ 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;
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 850a88abd33b..24da9a2ce070 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -245,7 +245,7 @@ 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_name(buf)) {
 			trace_probe_log_err(offset, BAD_GROUP_NAME);
 			return -EINVAL;
-- 
2.35.1

Re: [PATCH] kernel: move from strlcpy with unused retval to strscpy

[Steven Rostedt]

On Thu, 18 Aug 2022 23:02:01 +0200
Wolfram Sang <wsa+renesas@sang-engineering.com> wrote:

> Follow the advice of the below link and prefer 'strscpy' in this
> subsystem. Conversion is 1:1 because the return value is not used.
> Generated by a coccinelle script.
> 
> Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/

Grumble.

"So it's a completely useless function if you can't implicitly trust
the source string - but that is almost always why people think they
should use it!"

But in my cases I actually do trust the source string. They are all
generated from the kernel (not user input). With the exception of the
trace_inject, which I didn't write, and that should definitely be converted.

But eh, I'm not going to argue this one.

-- Steve

Re: [PATCH] kernel: move from strlcpy with unused retval to strscpy

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 343 bytes --]

Hi Steven,

> But in my cases I actually do trust the source string. They are all

The ultimate goal is to remove strlcpy entirely. My motivation is to get
rid of the extra work for maintainers that they need to ensure that the
author of a patch paid attention to the detail that the source string
must be trusted.

Happy hacking,

   Wolfram

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Re: [PATCH] kernel: move from strlcpy with unused retval to strscpy

[Steven Rostedt]

On Fri, 19 Aug 2022 07:53:51 +0200
Wolfram Sang <wsa+renesas@sang-engineering.com> wrote:

> > But in my cases I actually do trust the source string. They are all  
> 
> The ultimate goal is to remove strlcpy entirely. My motivation is to get
> rid of the extra work for maintainers that they need to ensure that the
> author of a patch paid attention to the detail that the source string
> must be trusted.

After reading Linus's rant, I figured as much.

-- Steve

Re: [PATCH] kernel: move from strlcpy with unused retval to strscpy

[Petr Mladek]

On Thu 2022-08-18 23:02:01, Wolfram Sang wrote:
> Follow the advice of the below link and prefer 'strscpy' in this
> subsystem. Conversion is 1:1 because the return value is not used.
> Generated by a coccinelle script.
> 
> Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
>
> ---
>  kernel/acct.c                         |  2 +-
>  kernel/bpf/preload/bpf_preload_kern.c |  4 ++--
>  kernel/cgroup/cgroup-v1.c             |  4 ++--
>  kernel/events/core.c                  |  6 +++---
>  kernel/kallsyms.c                     |  4 ++--
>  kernel/params.c                       |  2 +-
>  kernel/printk/printk.c                |  2 +-
>  kernel/relay.c                        |  4 ++--
>  kernel/time/clocksource.c             |  2 +-
>  kernel/trace/ftrace.c                 | 18 +++++++++---------
>  kernel/trace/trace.c                  |  8 ++++----
>  kernel/trace/trace_events.c           |  2 +-
>  kernel/trace/trace_events_inject.c    |  4 ++--
>  kernel/trace/trace_kprobe.c           |  2 +-
>  kernel/trace/trace_probe.c            |  2 +-
>  15 files changed, 33 insertions(+), 33 deletions(-)

This fixes only small part of the kernel code. It would make sense to
do a tree-wide change using a script.

Would you mind to create one and send it to Linus?

You might want to use Coccinelle if a simple sed/awk gets too
complicated. See
https://www.kernel.org/doc/html/v4.15/dev-tools/coccinelle.html

Best Regards,
Petr

Re: [PATCH] kernel: move from strlcpy with unused retval to strscpy

[Wolfram Sang]

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> > Generated by a coccinelle script.
^ ^ ^

> You might want to use Coccinelle if a simple sed/awk gets too
> complicated. See

:)

So, I did a tree wide conversion and let Linus know that I have a branch
available. He didn't respond, so I assumed that individual patches is
the way to go.


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Re: [PATCH] kernel: move from strlcpy with unused retval to strscpy

[Petr Mladek]

On Thu 2022-08-25 14:40:26, Wolfram Sang wrote:
> 
> > > Generated by a coccinelle script.
> ^ ^ ^
> 
> > You might want to use Coccinelle if a simple sed/awk gets too
> > complicated. See
> 
> :)
> 
> So, I did a tree wide conversion and let Linus know that I have a branch
> available. He didn't respond, so I assumed that individual patches is
> the way to go.

I am not sure when exactly you sent it. Linus is very busy during the
merge window and might miss less important things.

Also he might prefer to get the script that did the tree-wide change so
that he knows what exactly has changed.

Best Regards,
Petr

Re: [PATCH] kernel: move from strlcpy with unused retval to strscpy

[Wolfram Sang]

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> Also he might prefer to get the script that did the tree-wide change so
> that he knows what exactly has changed.

The script was also published in the thread originating all this [1].

[1] https://lore.kernel.org/all/YvhXzarjOLEJ8nsW@shikoro/


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