From 60034e0aedf507888c4a880f57011bb7f5d7700c Mon Sep 17 00:00:00 2001 From: Lee Jones Date: Wed, 13 Dec 2023 16:42:32 +0000 Subject: [PATCH] usb: gadget: f_uac2: 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 Cc: James Gruber Cc: Yadwinder Singh Cc: Jaswinder Singh Cc: Ruslan Bilovol Signed-off-by: Lee Jones Link: https://lore.kernel.org/r/20231213164246.1021885-4-lee@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_uac2.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c index f9a0f07a7476..383f6854cfec 100644 --- a/drivers/usb/gadget/function/f_uac2.c +++ b/drivers/usb/gadget/function/f_uac2.c @@ -2045,7 +2045,7 @@ static ssize_t f_uac2_opts_##name##_show(struct config_item *item, \ int result; \ \ mutex_lock(&opts->lock); \ - result = snprintf(page, sizeof(opts->name), "%s", opts->name); \ + result = scnprintf(page, sizeof(opts->name), "%s", opts->name); \ mutex_unlock(&opts->lock); \ \ return result; \ @@ -2063,7 +2063,7 @@ static ssize_t f_uac2_opts_##name##_store(struct config_item *item, \ goto end; \ } \ \ - ret = snprintf(opts->name, min(sizeof(opts->name), len), \ + ret = scnprintf(opts->name, min(sizeof(opts->name), len), \ "%s", page); \ \ end: \ @@ -2187,7 +2187,7 @@ static struct usb_function_instance *afunc_alloc_inst(void) opts->req_number = UAC2_DEF_REQ_NUM; opts->fb_max = FBACK_FAST_MAX; - snprintf(opts->function_name, sizeof(opts->function_name), "Source/Sink"); + scnprintf(opts->function_name, sizeof(opts->function_name), "Source/Sink"); opts->p_terminal_type = UAC2_DEF_P_TERM_TYPE; opts->c_terminal_type = UAC2_DEF_C_TERM_TYPE;