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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 <lee@kernel.org>
Link: https://lore.kernel.org/r/20231213164246.1021885-2-lee@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lee Jones 2023-12-13 16:42:30 +00:00 committed by Greg Kroah-Hartman
parent b8fb6db6cb
commit 0466e7e693
1 changed files with 7 additions and 4 deletions
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11
drivers/usb/gadget/configfs.c
View File

@ -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");