Re: [PATCH] net: sched: em_text: fix possible memory leak in em_text_destroy()

[Hangyu Hua]

On 21/12/2023 00:05, Jamal Hadi Salim wrote:
> On Wed, Dec 20, 2023 at 6:55 AM Jamal Hadi Salim <jhs@xxxxxxxxxxxx> wrote:
> > Hi Hangyu,
> > While the fix looks correct - can you please describe how you came
> > across this issue? Was it a tool or by inspection? Do you have a text
> > case that triggered something etc, etc.

I discovered this accidentally when I used gdb to debug a program that 
uses em_text. And I think putting the code in the commit log will will 
make it too bulky.

> > On Tue, Dec 19, 2023 at 10:09 PM Hangyu Hua <hbh25y@xxxxxxxxx> wrote:
> > > m->data needs to be freed when em_text_destroy is called.
> > >
> > > Fixes: d675c989ed2d ("[PKT_SCHED]: Packet classification based on textsearch (ematch)")
> > > Signed-off-by: Hangyu Hua <hbh25y@xxxxxxxxx>
> > > ---
> > >   net/sched/em_text.c | 4 +++-
> > >   1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/net/sched/em_text.c b/net/sched/em_text.c
> > > index 6f3c1fb2fb44..b9d5d4dca2c9 100644
> > > --- a/net/sched/em_text.c
> > > +++ b/net/sched/em_text.c
> > > @@ -97,8 +97,10 @@ static int em_text_change(struct net *net, void *data, int len,
> > >
> > >   static void em_text_destroy(struct tcf_ematch *m)
> > >   {
> > > -       if (EM_TEXT_PRIV(m) && EM_TEXT_PRIV(m)->config)
> > > +       if (EM_TEXT_PRIV(m) && EM_TEXT_PRIV(m)->config) {
> > >                  textsearch_destroy(EM_TEXT_PRIV(m)->config);
> > > +               kfree(m->data);
> > > +       }
> > >   }
>
> the bot just complained about needing a cast, use this:
> struct text_match *

I see. I will send a v2 later.

Thanks,
Hangyu

> cheers,
> jamal
> > Acked-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
> >
> > cheers,
> > jamal
> >
> > >   static int em_text_dump(struct sk_buff *skb, struct tcf_ematch *m)
> > > --
> > > 2.34.1