From 0466e7e693efe6647f23532529a9c41a1fa5f4ac Mon Sep 17 00:00:00 2001 From: Lee Jones Date: Wed, 13 Dec 2023 16:42:30 +0000 Subject: 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: Lee Jones Link: https://lore.kernel.org/r/20231213164246.1021885-2-lee@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/configfs.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'drivers/usb/gadget') diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c index b7d2a1313a68..ce3cfa1f36f5 100644 --- a/drivers/usb/gadget/configfs.c +++ b/drivers/usb/gadget/configfs.c @@ -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"); -- cgit v1.2.3