Commit 0466e7e6 authored by Lee Jones's avatar Lee Jones Committed by Greg Kroah-Hartman
Browse files

usb: gadget: configfs: Replace snprintf() with the safer scnprintf() variant 

There is a general misunderstanding amongst engineers that {v}snprintf()
returns the length of the data *actually* encoded into the destination
array.  However, as per the C99 standard {v}snprintf() really returns
the length of the data that *would have been* written if there were
enough space for it.  This misunderstanding has led to buffer-overruns
in the past.  It's generally considered safer to use the {v}scnprintf()
variants in their place (or even sprintf() in simple cases).  So let's
do that.

Link: https://lwn.net/Articles/69419/
Link: https://github.com/KSPP/linux/issues/105


Signed-off-by: default avatarLee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20231213164246.1021885-2-lee@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b8fb6db6

drivers/usb/gadget/configfs.c

+7 −4
Original line number Diff line number Diff line
@@ -606,10 +606,11 @@ static struct config_group *function_make( 
	char *instance_name;

	int ret;



	ret = snprintf(buf, MAX_NAME_LEN, "%s", name);

	if (ret >= MAX_NAME_LEN)

	if (strlen(name) >= MAX_NAME_LEN)

		return ERR_PTR(-ENAMETOOLONG);



	scnprintf(buf, MAX_NAME_LEN, "%s", name);



	func_name = buf;

	instance_name = strchr(func_name, '.');

	if (!instance_name) {
@@ -701,10 +702,12 @@ static struct config_group *config_desc_make( 
	int ret;



	gi = container_of(group, struct gadget_info, configs_group);

	ret = snprintf(buf, MAX_NAME_LEN, "%s", name);

	if (ret >= MAX_NAME_LEN)



	if (strlen(name) >= MAX_NAME_LEN)

		return ERR_PTR(-ENAMETOOLONG);



	scnprintf(buf, MAX_NAME_LEN, "%s", name);



	num_str = strchr(buf, '.');

	if (!num_str) {

		pr_err("Unable to locate . in name.bConfigurationValue\n");