From 71c4471290abc5888cf1cb13a7661e06367d3c5f Mon Sep 17 00:00:00 2001
From: Jamal Hadi Salim <jhs@mojatatu.com>
Date: Sun, 1 Jan 2023 16:57:44 -0500
Subject: [PATCH 1/2] net: sched: cbq: dont intepret cls results when asked to
drop
Git-commit: caa4b35b4317d5147b3ab0fbdc9c075c7d2e9c12
References: bsc#1207036 CVE-2023-23454
Patch-mainline: v6.2-rc3
If asked to drop a packet via TC_ACT_SHOT it is unsafe to assume that
res.class contains a valid pointer
Sample splat reported by Kyle Zeng
[ 5.405624] 0: reclassify loop, rule prio 0, protocol 800
[ 5.406326] ==================================================================
[ 5.407240] BUG: KASAN: slab-out-of-bounds in cbq_enqueue+0x54b/0xea0
[ 5.407987] Read of size 1 at addr ffff88800e3122aa by task poc/299
[ 5.408731]
[ 5.408897] CPU: 0 PID: 299 Comm: poc Not tainted 5.10.155+ #15
[ 5.409516] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.15.0-1 04/01/2014
[ 5.410439] Call Trace:
[ 5.410764] dump_stack+0x87/0xcd
[ 5.411153] print_address_description+0x7a/0x6b0
[ 5.411687] ? vprintk_func+0xb9/0xc0
[ 5.411905] ? printk+0x76/0x96
[ 5.412110] ? cbq_enqueue+0x54b/0xea0
[ 5.412323] kasan_report+0x17d/0x220
[ 5.412591] ? cbq_enqueue+0x54b/0xea0
[ 5.412803] __asan_report_load1_noabort+0x10/0x20
[ 5.413119] cbq_enqueue+0x54b/0xea0
[ 5.413400] ? __kasan_check_write+0x10/0x20
[ 5.413679] __dev_queue_xmit+0x9c0/0x1db0
[ 5.413922] dev_queue_xmit+0xc/0x10
[ 5.414136] ip_finish_output2+0x8bc/0xcd0
[ 5.414436] __ip_finish_output+0x472/0x7a0
[ 5.414692] ip_finish_output+0x5c/0x190
[ 5.414940] ip_output+0x2d8/0x3c0
[ 5.415150] ? ip_mc_finish_output+0x320/0x320
[ 5.415429] __ip_queue_xmit+0x753/0x1760
[ 5.415664] ip_queue_xmit+0x47/0x60
[ 5.415874] __tcp_transmit_skb+0x1ef9/0x34c0
[ 5.416129] tcp_connect+0x1f5e/0x4cb0
[ 5.416347] tcp_v4_connect+0xc8d/0x18c0
[ 5.416577] __inet_stream_connect+0x1ae/0xb40
[ 5.416836] ? local_bh_enable+0x11/0x20
[ 5.417066] ? lock_sock_nested+0x175/0x1d0
[ 5.417309] inet_stream_connect+0x5d/0x90
[ 5.417548] ? __inet_stream_connect+0xb40/0xb40
[ 5.417817] __sys_connect+0x260/0x2b0
[ 5.418037] __x64_sys_connect+0x76/0x80
[ 5.418267] do_syscall_64+0x31/0x50
[ 5.418477] entry_SYSCALL_64_after_hwframe+0x61/0xc6
[ 5.418770] RIP: 0033:0x473bb7
[ 5.418952] Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00
00 00 90 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2a 00 00
00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 18 89 54 24 0c 48 89 34
24 89
[ 5.420046] RSP: 002b:00007fffd20eb0f8 EFLAGS: 00000246 ORIG_RAX:
000000000000002a
[ 5.420472] RAX: ffffffffffffffda RBX: 00007fffd20eb578 RCX: 0000000000473bb7
[ 5.420872] RDX: 0000000000000010 RSI: 00007fffd20eb110 RDI: 0000000000000007
[ 5.421271] RBP: 00007fffd20eb150 R08: 0000000000000001 R09: 0000000000000004
[ 5.421671] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
[ 5.422071] R13: 00007fffd20eb568 R14: 00000000004fc740 R15: 0000000000000002
[ 5.422471]
[ 5.422562] Allocated by task 299:
[ 5.422782] __kasan_kmalloc+0x12d/0x160
[ 5.423007] kasan_kmalloc+0x5/0x10
[ 5.423208] kmem_cache_alloc_trace+0x201/0x2e0
[ 5.423492] tcf_proto_create+0x65/0x290
[ 5.423721] tc_new_tfilter+0x137e/0x1830
[ 5.423957] rtnetlink_rcv_msg+0x730/0x9f0
[ 5.424197] netlink_rcv_skb+0x166/0x300
[ 5.424428] rtnetlink_rcv+0x11/0x20
[ 5.424639] netlink_unicast+0x673/0x860
[ 5.424870] netlink_sendmsg+0x6af/0x9f0
[ 5.425100] __sys_sendto+0x58d/0x5a0
[ 5.425315] __x64_sys_sendto+0xda/0xf0
[ 5.425539] do_syscall_64+0x31/0x50
[ 5.425764] entry_SYSCALL_64_after_hwframe+0x61/0xc6
[ 5.426065]
[ 5.426157] The buggy address belongs to the object at ffff88800e312200
[ 5.426157] which belongs to the cache kmalloc-128 of size 128
[ 5.426955] The buggy address is located 42 bytes to the right of
[ 5.426955] 128-byte region [ffff88800e312200, ffff88800e312280)
[ 5.427688] The buggy address belongs to the page:
[ 5.427992] page:000000009875fabc refcount:1 mapcount:0
mapping:0000000000000000 index:0x0 pfn:0xe312
[ 5.428562] flags: 0x100000000000200(slab)
[ 5.428812] raw: 0100000000000200 dead000000000100 dead000000000122
ffff888007843680
[ 5.429325] raw: 0000000000000000 0000000000100010 00000001ffffffff
ffff88800e312401
[ 5.429875] page dumped because: kasan: bad access detected
[ 5.430214] page->mem_cgroup:ffff88800e312401
[ 5.430471]
[ 5.430564] Memory state around the buggy address:
[ 5.430846] ffff88800e312180: fc fc fc fc fc fc fc fc fc fc fc fc
fc fc fc fc
[ 5.431267] ffff88800e312200: 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 fc
[ 5.431705] >ffff88800e312280: fc fc fc fc fc fc fc fc fc fc fc fc
fc fc fc fc
[ 5.432123] ^
[ 5.432391] ffff88800e312300: 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 fc
[ 5.432810] ffff88800e312380: fc fc fc fc fc fc fc fc fc fc fc fc
fc fc fc fc
[ 5.433229] ==================================================================
[ 5.433648] Disabling lock debugging due to kernel taint
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Kyle Zeng <zengyhkyle@gmail.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
net/sched/sch_cbq.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 39b427dc7512..845f62c82ab4 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -231,6 +231,8 @@ cbq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
result = tcf_classify(skb, fl, &res, true);
if (!fl || result < 0)
goto fallback;
+ if (result == TC_ACT_SHOT)
+ return NULL;
cl = (void *)res.class;
if (!cl) {
@@ -251,8 +253,6 @@ cbq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
case TC_ACT_TRAP:
*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
/* fall through */
- case TC_ACT_SHOT:
- return NULL;
case TC_ACT_RECLASSIFY:
return cbq_reclassify(skb, cl);
}
--
2.16.4