[PATCH 5.14 134/172] net: sched: flower: protect fl_walk() with rcu

Greg Kroah-Hartman
2021-10-04T13:41:08Z

From: Vlad Buslov <vladbu@nvidia.com>

[ Upstream commit d5ef190693a7d76c5c192d108e8dec48307b46ee ]

Patch that refactored fl_walk() to use idr_for_each_entry_continue_ul()
also removed rcu protection of individual filters which causes following
use-after-free when filter is deleted concurrently. Fix fl_walk() to obtain
rcu read lock while iterating and taking the filter reference and temporary
release the lock while calling arg->fn() callback that can sleep.

KASAN trace:

[ 352.773640] ==================================================================
[ 352.775041] BUG: KASAN: use-after-free in fl_walk+0x159/0x240 [cls_flower]
[ 352.776304] Read of size 4 at addr ffff8881c8251480 by task tc/2987

[ 352.777862] CPU: 3 PID: 2987 Comm: tc Not tainted 5.15.0-rc2+ #2
[ 352.778980] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 352.781022] Call Trace:
[ 352.781573] dump_stack_lvl+0x46/0x5a
[ 352.782332] print_address_description.constprop.0+0x1f/0x140
[ 352.783400] ? fl_walk+0x159/0x240 [cls_flower]
[ 352.784292] ? fl_walk+0x159/0x240 [cls_flower]
[ 352.785138] kasan_report.cold+0x83/0xdf
[ 352.785851] ? fl_walk+0x159/0x240 [cls_flower]
[ 352.786587] kasan_check_range+0x145/0x1a0
[ 352.787337] fl_walk+0x159/0x240 [cls_flower]
[ 352.788163] ? fl_put+0x10/0x10 [cls_flower]
[ 352.789007] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220
[ 352.790102] tcf_chain_dump+0x231/0x450
[ 352.790878] ? tcf_chain_tp_delete_empty+0x170/0x170
[ 352.791833] ? __might_sleep+0x2e/0xc0
[ 352.792594] ? tfilter_notify+0x170/0x170
[ 352.793400] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220
[ 352.794477] tc_dump_tfilter+0x385/0x4b0
[ 352.795262] ? tc_new_tfilter+0x1180/0x1180
[ 352.796103] ? __mod_node_page_state+0x1f/0xc0
[ 352.796974] ? __build_skb_around+0x10e/0x130
[ 352.797826] netlink_dump+0x2c0/0x560
[ 352.798563] ? netlink_getsockopt+0x430/0x430
[ 352.799433] ? __mutex_unlock_slowpath.constprop.0+0x220/0x220
[ 352.800542] __netlink_dump_start+0x356/0x440
[ 352.801397] rtnetlink_rcv_msg+0x3ff/0x550
[ 352.802190] ? tc_new_tfilter+0x1180/0x1180
[ 352.802872] ? rtnl_calcit.isra.0+0x1f0/0x1f0
[ 352.803668] ? tc_new_tfilter+0x1180/0x1180
[ 352.804344] ? _copy_from_iter_nocache+0x800/0x800
[ 352.805202] ? kasan_set_track+0x1c/0x30
[ 352.805900] netlink_rcv_skb+0xc6/0x1f0
[ 352.806587] ? rht_deferred_worker+0x6b0/0x6b0
[ 352.807455] ? rtnl_calcit.isra.0+0x1f0/0x1f0
[ 352.808324] ? netlink_ack+0x4d0/0x4d0
[ 352.809086] ? netlink_deliver_tap+0x62/0x3d0
[ 352.809951] netlink_unicast+0x353/0x480
[ 352.810744] ? netlink_attachskb+0x430/0x430
[ 352.811586] ? __alloc_skb+0xd7/0x200
[ 352.812349] netlink_sendmsg+0x396/0x680
[ 352.813132] ? netlink_unicast+0x480/0x480
[ 352.813952] ? __import_iovec+0x192/0x210
[ 352.814759] ? netlink_unicast+0x480/0x480
[ 352.815580] sock_sendmsg+0x6c/0x80
[ 352.816299] ____sys_sendmsg+0x3a5/0x3c0
[ 352.817096] ? kernel_sendmsg+0x30/0x30
[ 352.817873] ? __ia32_sys_recvmmsg+0x150/0x150
[ 352.818753] ___sys_sendmsg+0xd8/0x140
[ 352.819518] ? sendmsg_copy_msghdr+0x110/0x110
[ 352.820402] ? ___sys_recvmsg+0xf4/0x1a0
[ 352.821110] ? __copy_msghdr_from_user+0x260/0x260
[ 352.821934] ? _raw_spin_lock+0x81/0xd0
[ 352.822680] ? __handle_mm_fault+0xef3/0x1b20
[ 352.823549] ? rb_insert_color+0x2a/0x270
[ 352.824373] ? copy_page_range+0x16b0/0x16b0
[ 352.825209] ? perf_event_update_userpage+0x2d0/0x2d0
[ 352.826190] ? __fget_light+0xd9/0xf0
[ 352.826941] __sys_sendmsg+0xb3/0x130
[ 352.827613] ? __sys_sendmsg_sock+0x20/0x20
[ 352.828377] ? do_user_addr_fault+0x2c5/0x8a0
[ 352.829184] ? fpregs_assert_state_consistent+0x52/0x60
[ 352.830001] ? exit_to_user_mode_prepare+0x32/0x160
[ 352.830845] do_syscall_64+0x35/0x80
[ 352.831445] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 352.832331] RIP: 0033:0x7f7bee973c17
[ 352.833078] Code: 0c 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
[ 352.836202] RSP: 002b:00007ffcbb368e28 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[ 352.837524] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7bee973c17
[ 352.838715] RDX: 0000000000000000 RSI: 00007ffcbb368e50 RDI: 0000000000000003
[ 352.839838] RBP: 00007ffcbb36d090 R08: 00000000cea96d79 R09: 00007f7beea34a40
[ 352.841021] R10: 00000000004059bb R11: 0000000000000246 R12: 000000000046563f
[ 352.842208] R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffcbb36d088

[ 352.843784] Allocated by task 2960:
[ 352.844451] kasan_save_stack+0x1b/0x40
[ 352.845173] __kasan_kmalloc+0x7c/0x90
[ 352.845873] fl_change+0x282/0x22db [cls_flower]
[ 352.846696] tc_new_tfilter+0x6cf/0x1180
[ 352.847493] rtnetlink_rcv_msg+0x471/0x550
[ 352.848323] netlink_rcv_skb+0xc6/0x1f0
[ 352.849097] netlink_unicast+0x353/0x480
[ 352.849886] netlink_sendmsg+0x396/0x680
[ 352.850678] sock_sendmsg+0x6c/0x80
[ 352.851398] ____sys_sendmsg+0x3a5/0x3c0
[ 352.852202] ___sys_sendmsg+0xd8/0x140
[ 352.852967] __sys_sendmsg+0xb3/0x130
[ 352.853718] do_syscall_64+0x35/0x80
[ 352.854457] entry_SYSCALL_64_after_hwframe+0x44/0xae

[ 352.855830] Freed by task 7:
[ 352.856421] kasan_save_stack+0x1b/0x40
[ 352.857139] kasan_set_track+0x1c/0x30
[ 352.857854] kasan_set_free_info+0x20/0x30
[ 352.858609] __kasan_slab_free+0xed/0x130
[ 352.859348] kfree+0xa7/0x3c0
[ 352.859951] process_one_work+0x44d/0x780
[ 352.860685] worker_thread+0x2e2/0x7e0
[ 352.861390] kthread+0x1f4/0x220
[ 352.862022] ret_from_fork+0x1f/0x30

[ 352.862955] Last potentially related work creation:
[ 352.863758] kasan_save_stack+0x1b/0x40
[ 352.864378] kasan_record_aux_stack+0xab/0xc0
[ 352.865028] insert_work+0x30/0x160
[ 352.865617] __queue_work+0x351/0x670
[ 352.866261] rcu_work_rcufn+0x30/0x40
[ 352.866917] rcu_core+0x3b2/0xdb0
[ 352.867561] __do_softirq+0xf6/0x386

[ 352.868708] Second to last potentially related work creation:
[ 352.869779] kasan_save_stack+0x1b/0x40
[ 352.870560] kasan_record_aux_stack+0xab/0xc0
[ 352.871426] call_rcu+0x5f/0x5c0
[ 352.872108] queue_rcu_work+0x44/0x50
[ 352.872855] __fl_put+0x17c/0x240 [cls_flower]
[ 352.873733] fl_delete+0xc7/0x100 [cls_flower]
[ 352.874607] tc_del_tfilter+0x510/0xb30
[ 352.886085] rtnetlink_rcv_msg+0x471/0x550
[ 352.886875] netlink_rcv_skb+0xc6/0x1f0
[ 352.887636] netlink_unicast+0x353/0x480
[ 352.888285] netlink_sendmsg+0x396/0x680
[ 352.888942] sock_sendmsg+0x6c/0x80
[ 352.889583] ____sys_sendmsg+0x3a5/0x3c0
[ 352.890311] ___sys_sendmsg+0xd8/0x140
[ 352.891019] __sys_sendmsg+0xb3/0x130
[ 352.891716] do_syscall_64+0x35/0x80
[ 352.892395] entry_SYSCALL_64_after_hwframe+0x44/0xae

[ 352.893666] The buggy address belongs to the object at ffff8881c8251000
which belongs to the cache kmalloc-2k of size 2048
[ 352.895696] The buggy address is located 1152 bytes inside of
2048-byte region [ffff8881c8251000, ffff8881c8251800)
[ 352.897640] The buggy address belongs to the page:
[ 352.898492] page:00000000213bac35 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1c8250
[ 352.900110] head:00000000213bac35 order:3 compound_mapcount:0 compound_pincount:0
[ 352.901541] flags: 0x2ffff800010200(slab|head|node=0|zone=2|lastcpupid=0x1ffff)
[ 352.902908] raw: 002ffff800010200 0000000000000000 dead000000000122 ffff888100042f00
[ 352.904391] raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
[ 352.905861] page dumped because: kasan: bad access detected

[ 352.907323] Memory state around the buggy address:
[ 352.908218] ffff8881c8251380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 352.909471] ffff8881c8251400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 352.910735] >ffff8881c8251480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 352.912012] ^
[ 352.912642] ffff8881c8251500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 352.913919] ffff8881c8251580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 352.915185] ==================================================================

Fixes: d39d714969cd ("idr: introduce idr_for_each_entry_continue_ul()")
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Acked-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sched/cls_flower.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index d7869a984881..d2a4e31d963d 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -2188,18 +2188,24 @@ static void fl_walk(struct tcf_proto *tp, struct tcf_walker *arg,

arg->count = arg->skip;

+ rcu_read_lock();
idr_for_each_entry_continue_ul(&head->handle_idr, f, tmp, id) {
/* don't return filters that are being deleted */
if (!refcount_inc_not_zero(&f->refcnt))
continue;
+ rcu_read_unlock();
+
if (arg->fn(tp, f, arg) < 0) {
__fl_put(f);
arg->stop = 1;
+ rcu_read_lock();
break;
}
__fl_put(f);
arg->count++;
+ rcu_read_lock();
}
+ rcu_read_unlock();
arg->cookie = id;
}

--
2.33.0