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: Cristian Birsan <cristian.birsan@xxxxxxxxxxxxx>
Cc: Nicolas Ferre <nicolas.ferre@xxxxxxxxxxxxx>
Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Cc: Claudiu Beznea <claudiu.beznea@xxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
---
drivers/usb/host/max3421-hcd.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/usb/host/max3421-hcd.c b/drivers/usb/host/max3421-hcd.c
index d152d72de1269..9fe4f48b18980 100644
--- a/drivers/usb/host/max3421-hcd.c
+++ b/drivers/usb/host/max3421-hcd.c
@@ -1158,12 +1158,12 @@ dump_eps(struct usb_hcd *hcd)
end = dp + sizeof(ubuf);
*dp = '\0';
list_for_each_entry(urb, &ep->urb_list, urb_list) {
- ret = snprintf(dp, end - dp, " %p(%d.%s %d/%d)", urb,
- usb_pipetype(urb->pipe),
- usb_urb_dir_in(urb) ? "IN" : "OUT",
- urb->actual_length,
- urb->transfer_buffer_length);
- if (ret < 0 || ret >= end - dp)
+ ret = scnprintf(dp, end - dp, " %p(%d.%s %d/%d)", urb,
+ usb_pipetype(urb->pipe),
+ usb_urb_dir_in(urb) ? "IN" : "OUT",
+ urb->actual_length,
+ urb->transfer_buffer_length);
+ if (ret == end - dp - 1)
break; /* error or buffer full */
dp += ret;
}
@@ -1255,9 +1255,9 @@ max3421_handle_irqs(struct usb_hcd *hcd)
end = sbuf + sizeof(sbuf);
*dp = '\0';
for (i = 0; i < 16; ++i) {
- int ret = snprintf(dp, end - dp, " %lu",
- max3421_hcd->err_stat[i]);
- if (ret < 0 || ret >= end - dp)
+ int ret = scnprintf(dp, end - dp, " %lu",
+ max3421_hcd->err_stat[i]);
+ if (ret == end - dp - 1)
break; /* error or buffer full */
dp += ret;
}
--
2.43.0.472.g3155946c3a-goog
