| Message ID | 20240704093458.39198-1-chengen.du@canonical.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net/sched: Fix UAF when resolving a clash | expand |
On Thu, Jul 04, 2024 at 05:34:58PM +0800, Chengen Du wrote: > KASAN reports the following UAF: > > BUG: KASAN: slab-use-after-free in tcf_ct_flow_table_process_conn+0x12b/0x380 [act_ct] > Read of size 1 at addr ffff888c07603600 by task handler130/6469 > > Call Trace: > <IRQ> > dump_stack_lvl+0x48/0x70 > print_address_description.constprop.0+0x33/0x3d0 > print_report+0xc0/0x2b0 > kasan_report+0xd0/0x120 > __asan_load1+0x6c/0x80 > tcf_ct_flow_table_process_conn+0x12b/0x380 [act_ct] > tcf_ct_act+0x886/0x1350 [act_ct] > tcf_action_exec+0xf8/0x1f0 > fl_classify+0x355/0x360 [cls_flower] > __tcf_classify+0x1fd/0x330 > tcf_classify+0x21c/0x3c0 > sch_handle_ingress.constprop.0+0x2c5/0x500 > __netif_receive_skb_core.constprop.0+0xb25/0x1510 > __netif_receive_skb_list_core+0x220/0x4c0 > netif_receive_skb_list_internal+0x446/0x620 > napi_complete_done+0x157/0x3d0 > gro_cell_poll+0xcf/0x100 > __napi_poll+0x65/0x310 > net_rx_action+0x30c/0x5c0 > __do_softirq+0x14f/0x491 > __irq_exit_rcu+0x82/0xc0 > irq_exit_rcu+0xe/0x20 > common_interrupt+0xa1/0xb0 > </IRQ> > <TASK> > asm_common_interrupt+0x27/0x40 > > Allocated by task 6469: > kasan_save_stack+0x38/0x70 > kasan_set_track+0x25/0x40 > kasan_save_alloc_info+0x1e/0x40 > __kasan_krealloc+0x133/0x190 > krealloc+0xaa/0x130 > nf_ct_ext_add+0xed/0x230 [nf_conntrack] > tcf_ct_act+0x1095/0x1350 [act_ct] > tcf_action_exec+0xf8/0x1f0 > fl_classify+0x355/0x360 [cls_flower] > __tcf_classify+0x1fd/0x330 > tcf_classify+0x21c/0x3c0 > sch_handle_ingress.constprop.0+0x2c5/0x500 > __netif_receive_skb_core.constprop.0+0xb25/0x1510 > __netif_receive_skb_list_core+0x220/0x4c0 > netif_receive_skb_list_internal+0x446/0x620 > napi_complete_done+0x157/0x3d0 > gro_cell_poll+0xcf/0x100 > __napi_poll+0x65/0x310 > net_rx_action+0x30c/0x5c0 > __do_softirq+0x14f/0x491 > > Freed by task 6469: > kasan_save_stack+0x38/0x70 > kasan_set_track+0x25/0x40 > kasan_save_free_info+0x2b/0x60 > ____kasan_slab_free+0x180/0x1f0 > __kasan_slab_free+0x12/0x30 > slab_free_freelist_hook+0xd2/0x1a0 > __kmem_cache_free+0x1a2/0x2f0 > kfree+0x78/0x120 > nf_conntrack_free+0x74/0x130 [nf_conntrack] > nf_ct_destroy+0xb2/0x140 [nf_conntrack] > __nf_ct_resolve_clash+0x529/0x5d0 [nf_conntrack] > nf_ct_resolve_clash+0xf6/0x490 [nf_conntrack] > __nf_conntrack_confirm+0x2c6/0x770 [nf_conntrack] > tcf_ct_act+0x12ad/0x1350 [act_ct] > tcf_action_exec+0xf8/0x1f0 > fl_classify+0x355/0x360 [cls_flower] > __tcf_classify+0x1fd/0x330 > tcf_classify+0x21c/0x3c0 > sch_handle_ingress.constprop.0+0x2c5/0x500 > __netif_receive_skb_core.constprop.0+0xb25/0x1510 > __netif_receive_skb_list_core+0x220/0x4c0 > netif_receive_skb_list_internal+0x446/0x620 > napi_complete_done+0x157/0x3d0 > gro_cell_poll+0xcf/0x100 > __napi_poll+0x65/0x310 > net_rx_action+0x30c/0x5c0 > __do_softirq+0x14f/0x491 > > The ct may be dropped if a clash has been resolved but is still passed to > the tcf_ct_flow_table_process_conn function for further usage. This issue > can be fixed by retrieving ct from skb again after confirming conntrack. > > Fixes: 0cc254e5aa37 ("net/sched: act_ct: Offload connections with commit action") > Co-developed-by: Gerald Yang <gerald.yang@canonical.com> > Signed-off-by: Gerald Yang <gerald.yang@canonical.com> > Signed-off-by: Chengen Du <chengen.du@canonical.com> > --- > net/sched/act_ct.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c > index 2a96d9c1db65..079562f6ca71 100644 > --- a/net/sched/act_ct.c > +++ b/net/sched/act_ct.c > @@ -1077,6 +1077,13 @@ TC_INDIRECT_SCOPE int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a, > */ > if (nf_conntrack_confirm(skb) != NF_ACCEPT) > goto drop; Nitpick: I would add a newline character before the comment, as that seems to be the convention in this file for other comments. > + /* The ct may be dropped if a clash has been resolved, > + * so it's necessary to retrieve it from skb again to > + * prevent UAF. > + */ > + ct = nf_ct_get(skb, &ctinfo); > + if (!ct) > + goto drop; > } > > if (!skip_add) > -- > 2.43.0 > > The fix itself looks correct to me. However, there is no explicit tag where the patch is addressed. It should be "net" tree as this is a fix. It should look like: [PATCH net] Please check the patchwork warning for details. Thanks, Michal
On Thu, 4 Jul 2024 12:57:35 +0200 Michal Kubiak wrote:
> Please check the patchwork warning for details.
Please don't direct people to patchwork checks, it's not a public CI.
On Thu, Jul 04, 2024 at 07:30:59AM -0700, Jakub Kicinski wrote: > On Thu, 4 Jul 2024 12:57:35 +0200 Michal Kubiak wrote: > > Please check the patchwork warning for details. > > Please don't direct people to patchwork checks, it's not a public CI. My apologies! I wasn't aware of this rule. Michal
diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c index 2a96d9c1db65..079562f6ca71 100644 --- a/net/sched/act_ct.c +++ b/net/sched/act_ct.c @@ -1077,6 +1077,13 @@ TC_INDIRECT_SCOPE int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a, */ if (nf_conntrack_confirm(skb) != NF_ACCEPT) goto drop; + /* The ct may be dropped if a clash has been resolved, + * so it's necessary to retrieve it from skb again to + * prevent UAF. + */ + ct = nf_ct_get(skb, &ctinfo); + if (!ct) + goto drop; } if (!skip_add)
KASAN reports the following UAF: BUG: KASAN: slab-use-after-free in tcf_ct_flow_table_process_conn+0x12b/0x380 [act_ct] Read of size 1 at addr ffff888c07603600 by task handler130/6469 Call Trace: <IRQ> dump_stack_lvl+0x48/0x70 print_address_description.constprop.0+0x33/0x3d0 print_report+0xc0/0x2b0 kasan_report+0xd0/0x120 __asan_load1+0x6c/0x80 tcf_ct_flow_table_process_conn+0x12b/0x380 [act_ct] tcf_ct_act+0x886/0x1350 [act_ct] tcf_action_exec+0xf8/0x1f0 fl_classify+0x355/0x360 [cls_flower] __tcf_classify+0x1fd/0x330 tcf_classify+0x21c/0x3c0 sch_handle_ingress.constprop.0+0x2c5/0x500 __netif_receive_skb_core.constprop.0+0xb25/0x1510 __netif_receive_skb_list_core+0x220/0x4c0 netif_receive_skb_list_internal+0x446/0x620 napi_complete_done+0x157/0x3d0 gro_cell_poll+0xcf/0x100 __napi_poll+0x65/0x310 net_rx_action+0x30c/0x5c0 __do_softirq+0x14f/0x491 __irq_exit_rcu+0x82/0xc0 irq_exit_rcu+0xe/0x20 common_interrupt+0xa1/0xb0 </IRQ> <TASK> asm_common_interrupt+0x27/0x40 Allocated by task 6469: kasan_save_stack+0x38/0x70 kasan_set_track+0x25/0x40 kasan_save_alloc_info+0x1e/0x40 __kasan_krealloc+0x133/0x190 krealloc+0xaa/0x130 nf_ct_ext_add+0xed/0x230 [nf_conntrack] tcf_ct_act+0x1095/0x1350 [act_ct] tcf_action_exec+0xf8/0x1f0 fl_classify+0x355/0x360 [cls_flower] __tcf_classify+0x1fd/0x330 tcf_classify+0x21c/0x3c0 sch_handle_ingress.constprop.0+0x2c5/0x500 __netif_receive_skb_core.constprop.0+0xb25/0x1510 __netif_receive_skb_list_core+0x220/0x4c0 netif_receive_skb_list_internal+0x446/0x620 napi_complete_done+0x157/0x3d0 gro_cell_poll+0xcf/0x100 __napi_poll+0x65/0x310 net_rx_action+0x30c/0x5c0 __do_softirq+0x14f/0x491 Freed by task 6469: kasan_save_stack+0x38/0x70 kasan_set_track+0x25/0x40 kasan_save_free_info+0x2b/0x60 ____kasan_slab_free+0x180/0x1f0 __kasan_slab_free+0x12/0x30 slab_free_freelist_hook+0xd2/0x1a0 __kmem_cache_free+0x1a2/0x2f0 kfree+0x78/0x120 nf_conntrack_free+0x74/0x130 [nf_conntrack] nf_ct_destroy+0xb2/0x140 [nf_conntrack] __nf_ct_resolve_clash+0x529/0x5d0 [nf_conntrack] nf_ct_resolve_clash+0xf6/0x490 [nf_conntrack] __nf_conntrack_confirm+0x2c6/0x770 [nf_conntrack] tcf_ct_act+0x12ad/0x1350 [act_ct] tcf_action_exec+0xf8/0x1f0 fl_classify+0x355/0x360 [cls_flower] __tcf_classify+0x1fd/0x330 tcf_classify+0x21c/0x3c0 sch_handle_ingress.constprop.0+0x2c5/0x500 __netif_receive_skb_core.constprop.0+0xb25/0x1510 __netif_receive_skb_list_core+0x220/0x4c0 netif_receive_skb_list_internal+0x446/0x620 napi_complete_done+0x157/0x3d0 gro_cell_poll+0xcf/0x100 __napi_poll+0x65/0x310 net_rx_action+0x30c/0x5c0 __do_softirq+0x14f/0x491 The ct may be dropped if a clash has been resolved but is still passed to the tcf_ct_flow_table_process_conn function for further usage. This issue can be fixed by retrieving ct from skb again after confirming conntrack. Fixes: 0cc254e5aa37 ("net/sched: act_ct: Offload connections with commit action") Co-developed-by: Gerald Yang <gerald.yang@canonical.com> Signed-off-by: Gerald Yang <gerald.yang@canonical.com> Signed-off-by: Chengen Du <chengen.du@canonical.com> --- net/sched/act_ct.c | 7 +++++++ 1 file changed, 7 insertions(+)