On Fri, 2 Nov 2018 16:14:59 +0900
Masami Hiramatsu <mhira...@kernel.org> wrote:
> On Thu, 1 Nov 2018 15:10:14 -0400
> Steven Rostedt <rost...@goodmis.org> wrote:
>
> > On Thu, 1 Nov 2018 23:29:28 +0900
> > Masami Hiramatsu <mhira...@kernel.org> wrote:
> >
> > > Fix strpbrk()'s argument order, it must pass acceptable string
> > > in 2nd argument. Note that this can cause a kernel panic where
> > > it recovers backup character to code->data.
> > >
> > > Fixes: a6682814f371 ("tracing/kprobes: Allow kprobe-events to record
> > > module symbol")
> > > Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
> >
> > Thanks Masami,
> >
> > I'm pulling this and starting to test it.
>
> Thank you! I still couldn't believe how this bug passed through the tests...
I am too. I'm running tests with and without this patch, and the patch
doesn't appear to be making much difference.
Then I tested with this:
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 3ef15a6683c0..4ddafddf1343 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -516,6 +516,7 @@ void traceprobe_free_probe_arg(struct probe_arg
*arg) kfree(code->data);
code++;
}
+ printk("free arg->code %s\n", arg->code);
kfree(arg->code);
kfree(arg->name);
kfree(arg->comm);
@@ -535,11 +536,15 @@ int traceprobe_update_arg(struct probe_arg *arg)
if (code[1].op != FETCH_OP_IMM)
return -EINVAL;
+ tmp = strpbrk(code->data, "+-");
+ printk("first tmp tmp=%s\n", tmp);
tmp = strpbrk("+-", code->data);
+ printk("second tmp=%s data=%s\n", tmp,
code->data); if (tmp)
c = *tmp;
ret =
traceprobe_split_symbol_offset(code->data, &offset);
+ printk("third data=%s\n", code->data);
if (ret)
return ret;
@@ -547,6 +552,7 @@ int traceprobe_update_arg(struct probe_arg *arg)
(unsigned
long)kallsyms_lookup_name(code->data); if (tmp)
*tmp = c;
+ printk("forth data=%s\n", code->data);
if (!code[1].immediate)
return -ENOENT;
code[1].immediate += offset;
And I don't see where that code->data is used elsewhere. That is, why
even bother saving the character?
-- Steve
