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Date: Fri, 21 Aug 2020 22:28:47 +0900 From: Masami Hiramatsu <mhiramat@...nel.org> To: Masami Hiramatsu <mhiramat@...nel.org> Cc: Muchun Song <songmuchun@...edance.com>, naveen.n.rao@...ux.ibm.com, anil.s.keshavamurthy@...el.com, davem@...emloft.net, songliubraving@...com, linux-kernel@...r.kernel.org, Chengming Zhou <zhouchengming@...edance.com> Subject: Re: [PATCH] kprobes: Fix kill kprobe which has been marked as gone On Fri, 21 Aug 2020 21:28:43 +0900 Masami Hiramatsu <mhiramat@...nel.org> wrote: > Hi Muchun, > > On Thu, 20 Aug 2020 11:19:33 +0800 > Muchun Song <songmuchun@...edance.com> wrote: > > > If a kprobe is marked as gone, we should not kill it again. Otherwise, > > we can disarm the kprobe more than once. In that case, the statistics > > of kprobe_ftrace_enabled can unbalance which can lead to that kprobe > > do not work. > > > > Good catch! Hmm, I think we also need an assertion in > kill_kprobe() so that p is already gone. Anyway, this looks good to me. > > Acked-by: Masami Hiramatsu <mhiramat@...nel.org> > > Thanks! > > > Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler") BTW, this fixes older bug than this commit. Fixes: e8386a0cb22f ("kprobes: support probing module __exit function") Thank you, > > Signed-off-by: Muchun Song <songmuchun@...edance.com> > > Co-developed-by: Chengming Zhou <zhouchengming@...edance.com> > > Signed-off-by: Chengming Zhou <zhouchengming@...edance.com> > > --- > > kernel/kprobes.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > > index d36e2b017588..7bac3ea44ff4 100644 > > --- a/kernel/kprobes.c > > +++ b/kernel/kprobes.c > > @@ -2422,7 +2422,10 @@ static int kprobes_module_callback(struct notifier_block *nb, > > mutex_lock(&kprobe_mutex); > > for (i = 0; i < KPROBE_TABLE_SIZE; i++) { > > head = &kprobe_table[i]; > > - hlist_for_each_entry(p, head, hlist) > > + hlist_for_each_entry(p, head, hlist) { > > + if (kprobe_gone(p)) > > + continue; > > + > > if (within_module_init((unsigned long)p->addr, mod) || > > (checkcore && > > within_module_core((unsigned long)p->addr, mod))) { > > @@ -2439,6 +2442,7 @@ static int kprobes_module_callback(struct notifier_block *nb, > > */ > > kill_kprobe(p); > > } > > + } > > } > > if (val == MODULE_STATE_GOING) > > remove_module_kprobe_blacklist(mod); > > -- > > 2.11.0 > > > > > -- > Masami Hiramatsu <mhiramat@...nel.org> -- Masami Hiramatsu <mhiramat@...nel.org>
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