| Message ID | 20240710053747.13223-1-chengen.du@canonical.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 26488172b0292bed837b95a006a3f3431d1898c3 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v3] net/sched: Fix UAF when resolving a clash | expand |
Hello: This patch was applied to netdev/net.git (main) by Paolo Abeni <pabeni@redhat.com>: On Wed, 10 Jul 2024 13:37:47 +0800 you 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 > > [...] Here is the summary with links: - [net,v3] net/sched: Fix UAF when resolving a clash https://git.kernel.org/netdev/net/c/26488172b029 You are awesome, thank you!
diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c index 2a96d9c1db65..6fa3cca87d34 100644 --- a/net/sched/act_ct.c +++ b/net/sched/act_ct.c @@ -1077,6 +1077,14 @@ 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) + skip_add = true; } 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 | 8 ++++++++ 1 file changed, 8 insertions(+)