Commit 60034e0a authored by Lee Jones's avatar Lee Jones Committed by Greg Kroah-Hartman
Browse files

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 <jimmyjgruber@gmail.com>
Cc: Yadwinder Singh <yadi.brar01@gmail.com>
Cc: Jaswinder Singh <jaswinder.singh@linaro.org>
Cc: Ruslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: default avatarLee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20231213164246.1021885-4-lee@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c1a37186

drivers/usb/gadget/function/f_uac2.c

+3 −3
Original line number Diff line number Diff line
@@ -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;