Message ID | 20180110000754.13545-1-xiyou.wangcong@gmail.com |
---|---|
State | Changes Requested, archived |
Delegated to: | David Miller |
Headers | show |
Series | [net] tun: fix a memory leak for tfile->tx_array | expand |
On 2018年01月10日 08:07, Cong Wang wrote: > tfile->tun could be detached before we close the tun fd, > via tun_detach_all(), so it should not be used to check for > tfile->tx_array. > > Use the same logic as in tun_attach(), just test !tfile->deatched. > > Reported-by: Dmitry Vyukov <dvyukov@google.com> > Fixes: 1576d9860599 ("tun: switch to use skb array for tx") > Cc: Jason Wang <jasowang@redhat.com> > Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> > --- > drivers/net/tun.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index 4f4a842a1c9c..1a1f834440a6 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -613,6 +613,7 @@ static void tun_queue_purge(struct tun_file *tfile) > > static void __tun_detach(struct tun_file *tfile, bool clean) > { > + bool clean_tx_array = !tfile->detached; > struct tun_file *ntfile; > struct tun_struct *tun; > > @@ -657,7 +658,7 @@ static void __tun_detach(struct tun_file *tfile, bool clean) > tun->dev->reg_state == NETREG_REGISTERED) > unregister_netdevice(tun->dev); > } > - if (tun) > + if (clean_tx_array) > skb_array_cleanup(&tfile->tx_array); > sock_put(&tfile->sk); > } Looks like we may still leak if we do open attach detach close Should we do cleanup unconditionally? Thanks
On Tue, Jan 9, 2018 at 7:00 PM, Jason Wang <jasowang@redhat.com> wrote: > > > On 2018年01月10日 08:07, Cong Wang wrote: >> >> tfile->tun could be detached before we close the tun fd, >> via tun_detach_all(), so it should not be used to check for >> tfile->tx_array. >> >> Use the same logic as in tun_attach(), just test !tfile->deatched. >> >> Reported-by: Dmitry Vyukov <dvyukov@google.com> >> Fixes: 1576d9860599 ("tun: switch to use skb array for tx") >> Cc: Jason Wang <jasowang@redhat.com> >> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> >> --- >> drivers/net/tun.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/net/tun.c b/drivers/net/tun.c >> index 4f4a842a1c9c..1a1f834440a6 100644 >> --- a/drivers/net/tun.c >> +++ b/drivers/net/tun.c >> @@ -613,6 +613,7 @@ static void tun_queue_purge(struct tun_file *tfile) >> static void __tun_detach(struct tun_file *tfile, bool clean) >> { >> + bool clean_tx_array = !tfile->detached; >> struct tun_file *ntfile; >> struct tun_struct *tun; >> @@ -657,7 +658,7 @@ static void __tun_detach(struct tun_file *tfile, >> bool clean) >> tun->dev->reg_state == NETREG_REGISTERED) >> unregister_netdevice(tun->dev); >> } >> - if (tun) >> + if (clean_tx_array) >> skb_array_cleanup(&tfile->tx_array); >> sock_put(&tfile->sk); >> } > > > Looks like we may still leak if we do > > open > attach > detach > close Good catch. > > Should we do cleanup unconditionally? It doesn't look like we can, because tfile is not zero'ed at least, it is allocated by sk_alloc() so tfile->tx_array could be some random value which prevents skb_array_cleanup() functioning correctly. Zero'ing tfile->tx_array in open() is not sufficient, as spinlocks are not yet initialized. I think we probably need to test tfile->tx_array.ring.queue, it is ugly but I don't see there is an API for it.
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 4f4a842a1c9c..1a1f834440a6 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -613,6 +613,7 @@ static void tun_queue_purge(struct tun_file *tfile) static void __tun_detach(struct tun_file *tfile, bool clean) { + bool clean_tx_array = !tfile->detached; struct tun_file *ntfile; struct tun_struct *tun; @@ -657,7 +658,7 @@ static void __tun_detach(struct tun_file *tfile, bool clean) tun->dev->reg_state == NETREG_REGISTERED) unregister_netdevice(tun->dev); } - if (tun) + if (clean_tx_array) skb_array_cleanup(&tfile->tx_array); sock_put(&tfile->sk); }
tfile->tun could be detached before we close the tun fd, via tun_detach_all(), so it should not be used to check for tfile->tx_array. Use the same logic as in tun_attach(), just test !tfile->deatched. Reported-by: Dmitry Vyukov <dvyukov@google.com> Fixes: 1576d9860599 ("tun: switch to use skb array for tx") Cc: Jason Wang <jasowang@redhat.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> --- drivers/net/tun.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)