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: Ruslan Bilovol <ruslan.bilovol@xxxxxxxxx>
Cc: Julian Scheel <julian@xxxxxxxx>
Cc: Bryan Wu <cooloney@xxxxxxxxxx>
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
---
drivers/usb/gadget/function/f_uac1.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/gadget/function/f_uac1.c b/drivers/usb/gadget/function/f_uac1.c
index 6f0e1d803dc24..998e2331effb0 100644
--- a/drivers/usb/gadget/function/f_uac1.c
+++ b/drivers/usb/gadget/function/f_uac1.c
@@ -1561,7 +1561,7 @@ static ssize_t f_uac1_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; \
@@ -1579,7 +1579,7 @@ static ssize_t f_uac1_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: \
@@ -1685,7 +1685,7 @@ static struct usb_function_instance *f_audio_alloc_inst(void)
opts->req_number = UAC1_DEF_REQ_NUM;
- snprintf(opts->function_name, sizeof(opts->function_name), "AC Interface");
+ scnprintf(opts->function_name, sizeof(opts->function_name), "AC Interface");
return &opts->func_inst;
}
--
2.43.0.472.g3155946c3a-goog
