From: Jamal Hadi Salim jhs@mojatatu.com

[ Upstream commit caa4b35b4317d5147b3ab0fbdc9c075c7d2e9c12 ]

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 [Harshit: backport to 4.19.y] Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com --- Compile and boot tested. This is marked as Fix for CVE-2023-23454. Would be nice if any net developer review this before merging this to stable. --- 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 0a76ad05e5ae..2974f7262f88 100644 --- a/net/sched/sch_cbq.c +++ b/net/sched/sch_cbq.c @@ -236,6 +236,8 @@ 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) { @@ -256,8 +258,6 @@ 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); }