Messages in this thread | | | Date | Tue, 15 Sep 2009 09:29:35 -0400 | From | Masami Hiramatsu <> | Subject | Re: [BUGFIX] kprobes: prevent re-registration of the same kprobe - take2 |
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Ananth N Mavinakayanahalli wrote: > On Mon, Sep 14, 2009 at 12:25:41PM -0400, Masami Hiramatsu wrote: >> Ananth N Mavinakayanahalli wrote: >>> On Sun, Sep 13, 2009 at 09:47:39PM -0400, Masami Hiramatsu wrote: >>>> Ananth N Mavinakayanahalli wrote: >>>>> On Fri, Sep 11, 2009 at 05:12:54AM +0200, Frederic Weisbecker wrote: >>>>>> On Thu, Sep 10, 2009 at 07:53:30PM -0400, Masami Hiramatsu wrote: > > ... > >>> +static inline int check_kprobe_rereg(struct kprobe *p) >>> +{ >>> + int ret = 0; >>> + struct kprobe *old_p; >>> + >>> + mutex_lock(&kprobe_mutex); >>> + old_p = __get_valid_kprobe(p); >>> + if (old_p == p) >> >> Here, since __get_valid_kprobe(p) will return aggr_kprobe of 'p', >> you just need to check old_p != NULL. > > Right! > > --- > Prevent re-registration of the same kprobe. This situation, though > unlikely, needs to be flagged since it can lead to a system crash if its > not handled. > > The core change itself is small, but the helper routine needed to be > moved around a bit; hence the diffstat. > > Signed-off-by: Ananth N Mavinakayanahalli<ananth@in.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
> --- > kernel/kprobes.c | 58 ++++++++++++++++++++++++++++++++++++------------------- > 1 file changed, 38 insertions(+), 20 deletions(-) > > Index: linux-2.6.31/kernel/kprobes.c > =================================================================== > --- linux-2.6.31.orig/kernel/kprobes.c > +++ linux-2.6.31/kernel/kprobes.c > @@ -681,6 +681,40 @@ static kprobe_opcode_t __kprobes *kprobe > return (kprobe_opcode_t *)(((char *)addr) + p->offset); > } > > +/* Check passed kprobe is valid and return kprobe in kprobe_table. */ > +static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p) > +{ > + struct kprobe *old_p, *list_p; > + > + old_p = get_kprobe(p->addr); > + if (unlikely(!old_p)) > + return NULL; > + > + if (p != old_p) { > + list_for_each_entry_rcu(list_p, &old_p->list, list) > + if (list_p == p) > + /* kprobe p is a valid probe */ > + goto valid; > + return NULL; > + } > +valid: > + return old_p; > +} > + > +/* Return error if the kprobe is being re-registered */ > +static inline int check_kprobe_rereg(struct kprobe *p) > +{ > + int ret = 0; > + struct kprobe *old_p; > + > + mutex_lock(&kprobe_mutex); > + old_p = __get_valid_kprobe(p); > + if (old_p) > + ret = -EINVAL; > + mutex_unlock(&kprobe_mutex); > + return ret; > +} > + > int __kprobes register_kprobe(struct kprobe *p) > { > int ret = 0; > @@ -693,6 +727,10 @@ int __kprobes register_kprobe(struct kpr > return -EINVAL; > p->addr = addr; > > + ret = check_kprobe_rereg(p); > + if (ret) > + return ret; > + > preempt_disable(); > if (!kernel_text_address((unsigned long) p->addr) || > in_kprobes_functions((unsigned long) p->addr)) { > @@ -762,26 +800,6 @@ out: > } > EXPORT_SYMBOL_GPL(register_kprobe); > > -/* Check passed kprobe is valid and return kprobe in kprobe_table. */ > -static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p) > -{ > - struct kprobe *old_p, *list_p; > - > - old_p = get_kprobe(p->addr); > - if (unlikely(!old_p)) > - return NULL; > - > - if (p != old_p) { > - list_for_each_entry_rcu(list_p, &old_p->list, list) > - if (list_p == p) > - /* kprobe p is a valid probe */ > - goto valid; > - return NULL; > - } > -valid: > - return old_p; > -} > - > /* > * Unregister a kprobe without a scheduler synchronization. > */
-- Masami Hiramatsu
Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division
e-mail: mhiramat@redhat.com
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