From: Chengen Du <chengen.du@canonical.com>
To: jhs@mojatatu.com
Cc: xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net,
edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
ozsh@nvidia.com, paulb@nvidia.com, marcelo.leitner@gmail.com,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Chengen Du <chengen.du@canonical.com>,
Gerald Yang <gerald.yang@canonical.com>
Subject: [PATCH] net/sched: Fix UAF when resolving a clash
Date: Thu, 4 Jul 2024 17:34:58 +0800 [thread overview]
Message-ID: <20240704093458.39198-1-chengen.du@canonical.com> (raw)
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;
+ /* 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
next reply other threads:[~2024-07-04 9:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-04 9:34 Chengen Du [this message]
2024-07-04 10:57 ` Michal Kubiak
2024-07-04 14:30 ` Jakub Kicinski
2024-07-04 14:46 ` Michal Kubiak
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