[prev in list] [next in list] [prev in thread] [next in thread]
List: linux-rt-users
Subject: Re: [PATCH rt-tests v1 v1 1/4] pmqtest: Increase buffer to avoid overflow
From: John Kacur <jkacur () redhat ! com>
Date: 2019-08-23 15:15:58
Message-ID: alpine.LFD.2.21.1908231709170.7154 () planxty
[Download RAW message or body]
On Mon, 19 Aug 2019, Daniel Wagner wrote:
> Increase the size of the char buffer. gcc 9.1.1 reports:
>
> src/pmqtest/pmqtest.c: In function ‘main':
> src/pmqtest/pmqtest.c:46:21: warning: ‘%d' directive writing between 1 and 10 \
> bytes into a region of size 8 [-Wformat-overflow=] 46 | #define SYNCMQ_NAME \
> "/syncmsg%d" | ^~~~~~~~~~~~
>
> src/pmqtest/pmqtest.c:445:3: note: ‘sprintf' output between 10 and 19 bytes into \
> a destination of size 16 445 | sprintf(mqname, SYNCMQ_NAME, i);
> > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Signed-off-by: Daniel Wagner <wagi@monom.org>
> ---
> src/pmqtest/pmqtest.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/pmqtest/pmqtest.c b/src/pmqtest/pmqtest.c
> index a04fc49872bf..3ce799bd6319 100644
> --- a/src/pmqtest/pmqtest.c
> +++ b/src/pmqtest/pmqtest.c
> @@ -440,7 +440,7 @@ int main(int argc, char *argv[])
> goto nomem;
>
> for (i = 0; i < num_threads; i++) {
> - char mqname[16];
> + char mqname[19];
>
> sprintf(mqname, SYNCMQ_NAME, i);
> receiver[i].syncmq = mq_open(mqname, oflag, 0777, &mqstat);
> @@ -567,7 +567,7 @@ int main(int argc, char *argv[])
> }
> nanosleep(&maindelay, NULL);
> for (i = 0; i < num_threads; i++) {
> - char mqname[16];
> + char mqname[19];
>
> mq_close(receiver[i].syncmq);
> sprintf(mqname, SYNCMQ_NAME, i);
> --
> 2.21.0
>
I don't love the use of "magic numbers". Also the compiler considers the
signed integers to be −2147483648 to 2147483647 so including the sign that
is potentially up to 11 chars, plus our string is "/syncmsg" is 8 chars
so that's where the 19 comes from. However we are using the int to
represent threads, so we know we can't have a negative number. However
sprintf also adds '\n' which brings us back to 19 again anyway.
This is better than what we have, so
Signed-off-by: John Kacur <jkacur@redhat.com>
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic