Re: [PATCH net] sctp: fix dst reference leak in sctp_v4_get_dst
On 05.02.2018 03:01, Marcelo Ricardo Leitner wrote: Hi, On Sun, Feb 04, 2018 at 11:02:39AM +0200, Tommi Rantala wrote: Fix dst reference leak in sctp_v4_get_dst() introduced in commit 410f03831 ("sctp: add routing output fallback"): When walking the address_list, successive ip_route_output_key() calls may return the same rt->dst with the reference incremented on each call. The code would not decrement the dst refcount when the dst pointer was identical from the previous iteration, causing the dst leak. Ugh, I think this patch still does not get the refcounting right, please don't apply. For example: - on first iteration of the loop: "odev" check fails, and we set dst with refcnt=1. - on second iteration: the same dst refcnt is incremented to 2 via ip_route_output_key(). "odev" check succeeds. dst == &rt->dst, so we do not touch the refcnt. break out of the loop => oops, dst has refcnt=2 Testcase: ip netns add TEST ip netns exec TEST ip link set lo up ip link add dummy0 type dummy ip link add dummy1 type dummy ip link add dummy2 type dummy ip link set dev dummy0 netns TEST ip link set dev dummy1 netns TEST ip link set dev dummy2 netns TEST ip netns exec TEST ip addr add 192.168.1.1/24 dev dummy0 ip netns exec TEST ip link set dummy0 up ip netns exec TEST ip addr add 192.168.1.2/24 dev dummy1 ip netns exec TEST ip link set dummy1 up ip netns exec TEST ip addr add 192.168.1.3/24 dev dummy2 ip netns exec TEST ip link set dummy2 up ip netns exec TEST sctp_test -H 192.168.1.2 -P 20002 -h 192.168.1.1 -p 2 -s -B 192.168.1.3 ip netns del TEST Thanks for the detailed steps. I'll adapt and include it on github/sctp/sctp-tests ok, good! In 4.4 and 4.9 kernels this results to: I wonder why you couldn't reproduce this on newer kernels. Maybe something masked it? I didn't check what exactly changed here. commit 955ec4cb3b54c7c389a9f830be7d3ae2056b9212 was mentioned elsewhere. Also the commits by Wei Wang changed the dst handling, see e.g. 5b7c9a8ff828287af5aebe93e707271bf1a82cc3 [ 354.179591] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 364.419674] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 374.663664] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 384.903717] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 395.143724] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 405.383645] unregister_netdevice: waiting for lo to become free. Usage count = 1 ... Fixes: 410f03831 ("sctp: add routing output fallback") Acked-by: Neil Horman Cc: Marcelo Ricardo Leitner Cc: Alexey Kodanev Signed-off-by: Tommi Rantala --- net/sctp/protocol.c | 9 - 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c index 8b4ff315695e..aadb9e7f60e2 100644 --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -508,21 +508,20 @@ static void sctp_v4_get_dst(struct sctp_transport *t, union sctp_addr *saddr, if (IS_ERR(rt)) continue; - if (!dst) - dst = &rt->dst; - /* Ensure the src address belongs to the output * interface. */ odev = __ip_dev_find(sock_net(sk), laddr->a.v4.sin_addr.s_addr, false); if (!odev || odev->ifindex != fl4->flowi4_oif) { - if (&rt->dst != dst) + if (!dst) + dst = &rt->dst; + else dst_release(&rt->dst); continue; } - if (dst != &rt->dst) + if (dst && dst != &rt->dst) dst_release(dst); dst = &rt->dst; break; -- 2.15.1 -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH net] sctp: fix dst reference leak in sctp_v4_get_dst
Hi, On Sun, Feb 04, 2018 at 11:02:39AM +0200, Tommi Rantala wrote: > Fix dst reference leak in sctp_v4_get_dst() introduced in commit > 410f03831 ("sctp: add routing output fallback"): > > When walking the address_list, successive ip_route_output_key() calls > may return the same rt->dst with the reference incremented on each call. > > The code would not decrement the dst refcount when the dst pointer was > identical from the previous iteration, causing the dst leak. > > Testcase: > ip netns add TEST > ip netns exec TEST ip link set lo up > ip link add dummy0 type dummy > ip link add dummy1 type dummy > ip link add dummy2 type dummy > ip link set dev dummy0 netns TEST > ip link set dev dummy1 netns TEST > ip link set dev dummy2 netns TEST > ip netns exec TEST ip addr add 192.168.1.1/24 dev dummy0 > ip netns exec TEST ip link set dummy0 up > ip netns exec TEST ip addr add 192.168.1.2/24 dev dummy1 > ip netns exec TEST ip link set dummy1 up > ip netns exec TEST ip addr add 192.168.1.3/24 dev dummy2 > ip netns exec TEST ip link set dummy2 up > ip netns exec TEST sctp_test -H 192.168.1.2 -P 20002 -h 192.168.1.1 -p > 2 -s -B 192.168.1.3 > ip netns del TEST Thanks for the detailed steps. I'll adapt and include it on github/sctp/sctp-tests > > In 4.4 and 4.9 kernels this results to: I wonder why you couldn't reproduce this on newer kernels. Maybe something masked it? > [ 354.179591] unregister_netdevice: waiting for lo to become free. Usage > count = 1 > [ 364.419674] unregister_netdevice: waiting for lo to become free. Usage > count = 1 > [ 374.663664] unregister_netdevice: waiting for lo to become free. Usage > count = 1 > [ 384.903717] unregister_netdevice: waiting for lo to become free. Usage > count = 1 > [ 395.143724] unregister_netdevice: waiting for lo to become free. Usage > count = 1 > [ 405.383645] unregister_netdevice: waiting for lo to become free. Usage > count = 1 > ... > > Fixes: 410f03831 ("sctp: add routing output fallback") > Acked-by: Neil Horman > Cc: Marcelo Ricardo Leitner > Cc: Alexey Kodanev > Signed-off-by: Tommi Rantala > --- > net/sctp/protocol.c | 9 - > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c > index 8b4ff315695e..aadb9e7f60e2 100644 > --- a/net/sctp/protocol.c > +++ b/net/sctp/protocol.c > @@ -508,21 +508,20 @@ static void sctp_v4_get_dst(struct sctp_transport *t, > union sctp_addr *saddr, > if (IS_ERR(rt)) > continue; > > - if (!dst) > - dst = &rt->dst; > - > /* Ensure the src address belongs to the output >* interface. >*/ > odev = __ip_dev_find(sock_net(sk), laddr->a.v4.sin_addr.s_addr, >false); > if (!odev || odev->ifindex != fl4->flowi4_oif) { > - if (&rt->dst != dst) > + if (!dst) > + dst = &rt->dst; > + else > dst_release(&rt->dst); > continue; > } > > - if (dst != &rt->dst) > + if (dst && dst != &rt->dst) > dst_release(dst); > dst = &rt->dst; > break; > -- > 2.15.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
[PATCH net] sctp: fix dst reference leak in sctp_v4_get_dst
Fix dst reference leak in sctp_v4_get_dst() introduced in commit 410f03831 ("sctp: add routing output fallback"): When walking the address_list, successive ip_route_output_key() calls may return the same rt->dst with the reference incremented on each call. The code would not decrement the dst refcount when the dst pointer was identical from the previous iteration, causing the dst leak. Testcase: ip netns add TEST ip netns exec TEST ip link set lo up ip link add dummy0 type dummy ip link add dummy1 type dummy ip link add dummy2 type dummy ip link set dev dummy0 netns TEST ip link set dev dummy1 netns TEST ip link set dev dummy2 netns TEST ip netns exec TEST ip addr add 192.168.1.1/24 dev dummy0 ip netns exec TEST ip link set dummy0 up ip netns exec TEST ip addr add 192.168.1.2/24 dev dummy1 ip netns exec TEST ip link set dummy1 up ip netns exec TEST ip addr add 192.168.1.3/24 dev dummy2 ip netns exec TEST ip link set dummy2 up ip netns exec TEST sctp_test -H 192.168.1.2 -P 20002 -h 192.168.1.1 -p 2 -s -B 192.168.1.3 ip netns del TEST In 4.4 and 4.9 kernels this results to: [ 354.179591] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 364.419674] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 374.663664] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 384.903717] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 395.143724] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 405.383645] unregister_netdevice: waiting for lo to become free. Usage count = 1 ... Fixes: 410f03831 ("sctp: add routing output fallback") Acked-by: Neil Horman Cc: Marcelo Ricardo Leitner Cc: Alexey Kodanev Signed-off-by: Tommi Rantala --- net/sctp/protocol.c | 9 - 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c index 8b4ff315695e..aadb9e7f60e2 100644 --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -508,21 +508,20 @@ static void sctp_v4_get_dst(struct sctp_transport *t, union sctp_addr *saddr, if (IS_ERR(rt)) continue; - if (!dst) - dst = &rt->dst; - /* Ensure the src address belongs to the output * interface. */ odev = __ip_dev_find(sock_net(sk), laddr->a.v4.sin_addr.s_addr, false); if (!odev || odev->ifindex != fl4->flowi4_oif) { - if (&rt->dst != dst) + if (!dst) + dst = &rt->dst; + else dst_release(&rt->dst); continue; } - if (dst != &rt->dst) + if (dst && dst != &rt->dst) dst_release(dst); dst = &rt->dst; break; -- 2.15.1