On 9/4/19 9:50 AM, Andrea Claudi wrote:
> gcc v9.2.1 produces the following warning compiling iproute2:
>
> bpf.c: In function ‘bpf_get_work_dir’:
> bpf.c:784:49: warning: ‘snprintf’ output may be truncated before the last
> format character [-Wformat-truncation=]
> 784 | snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt);
> | ^
> bpf.c:784:2: note: ‘snprintf’ output between 2 and 4097 bytes into a
> destination of size 4096
> 784 | snprintf(bpf_wrk_dir, sizeof(bpf_wrk_dir), "%s/", mnt);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Fix it extending bpf_wrk_dir size by 1 byte for the extra "/" char.
>
> Signed-off-by: Andrea Claudi <acla...@redhat.com>
> ---
> lib/bpf.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/bpf.c b/lib/bpf.c
> index 7d2a322ffbaec..95de7894a93ce 100644
> --- a/lib/bpf.c
> +++ b/lib/bpf.c
> @@ -742,7 +742,7 @@ static int bpf_gen_hierarchy(const char *base)
> static const char *bpf_get_work_dir(enum bpf_prog_type type)
> {
> static char bpf_tmp[PATH_MAX] = BPF_DIR_MNT;
> - static char bpf_wrk_dir[PATH_MAX];
> + static char bpf_wrk_dir[PATH_MAX + 1];
> static const char *mnt;
> static bool bpf_mnt_cached;
> const char *mnt_env = getenv(BPF_ENV_MNT);
>
PATH_MAX is meant to be the max length for a filesystem path including
the null terminator, so I think it would be better to change the
snprintf to 'sizeof(bpf_wrk_dir) - 1'.
