Re: [PATCH v9 tip 6/9] samples: bpf: simple non-portable kprobe filter example

[Alexei Starovoitov]

On 3/23/15 12:35 AM, Ingo Molnar wrote:
> * Alexei Starovoitov <ast@xxxxxxxxxxxx> wrote:
>
> > +void read_trace_pipe(void)
> > +{
> > +	int trace_fd;
> > +
> > +	trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
> > +	if (trace_fd < 0)
> > +		return;
> > +
> > +	while (1) {
> > +		static char buf[4096];
> > +		ssize_t sz;
> > +
> > +		sz = read(trace_fd, buf, sizeof(buf));
>
> read() will return -1 on failure ...
>
> > +		if (sz) {
>
> ... this test passes ...
>
> > +			buf[sz] = 0;
>
> ... and here we smash the stack?

good point. If it was normal file, for sure it's a bug, but trace_pipe
is a pseudo file and I think read cannot return -1. Regardless, it makes
sense to fix it. Will do. Do you mind I address it as follow up patch?
Or if the rest is ok, can you change the condition to sz>0 while
applying? I can respin the whole thing too, if you like.
Thanks!
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/