samples, bpf: fix to change the buffer size for read()

If the trace for read is larger than 4096, the return
value sz will be 4096. This results in off-by-one error
on buf:

    static char buf[4096];
    ssize_t sz;

    sz = read(trace_fd, buf, sizeof(buf));
    if (sz > 0) {
        buf[sz] = 0;
        puts(buf);
    }

Signed-off-by: Chang-Hsien Tsai <luke.tw@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Chang-Hsien Tsai 2019-05-19 09:05:44 +00:00 committed by Daniel Borkmann
parent f7355a6c04
commit f7c2d64bac

View file

@ -678,7 +678,7 @@ void read_trace_pipe(void)
static char buf[4096];
ssize_t sz;
sz = read(trace_fd, buf, sizeof(buf));
sz = read(trace_fd, buf, sizeof(buf) - 1);
if (sz > 0) {
buf[sz] = 0;
puts(buf);