rtc: fix snprintf() checking in is_rtc_hctosys()

The scnprintf() function silently truncates the printf() and returns
the number bytes that it was able to copy (not counting the NUL
terminator).  Thus, the highest value it can return here is
"NAME_SIZE - 1" and the overflow check is dead code.  Fix this by
using the snprintf() function which returns the number of bytes that
would have been copied if there was enough space and changing the
condition from "> NAME_SIZE" to ">= NAME_SIZE".

Fixes: 92589c986b33 ("rtc-proc: permit the /proc/driver/rtc device to use other devices")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/YJov/pcGmhLi2pEl@mwanda

diff --git a/drivers/rtc/proc.c b/drivers/rtc/proc.c
index 73344598fc1bef235f6341d2bcc5f4da3482e9a9..cbcdbb19d848e78e6674bd626833151a99773ef0 100644 (file)
--- a/drivers/rtc/proc.c
+++ b/drivers/rtc/proc.c
@@ -23,8 +23,8 @@ static bool is_rtc_hctosys(struct rtc_device *rtc)
        int size;
        char name[NAME_SIZE];
 
-       size = scnprintf(name, NAME_SIZE, "rtc%d", rtc->id);
-       if (size > NAME_SIZE)
+       size = snprintf(name, NAME_SIZE, "rtc%d", rtc->id);
+       if (size >= NAME_SIZE)
                return false;
 
        return !strncmp(name, CONFIG_RTC_HCTOSYS_DEVICE, NAME_SIZE);