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Message-Id: <40b45f70ef007b222b36a4676174e597c41d697f.1529415169.git.dcaratti@redhat.com>
Date: Tue, 19 Jun 2018 15:39:46 +0200
From: Davide Caratti <dcaratti@...hat.com>
To: Jamal Hadi Salim <jhs@...atatu.com>,
Cong Wang <xiyou.wangcong@...il.com>
Cc: "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: [PATCH net] net/sched: act_ife: fix recursive lock and idr leak
a recursive lock warning [1] can be observed with the following script,
# $TC actions add action ife encode allow prio pass index 42
IFE type 0xED3E
# $TC actions replace action ife encode allow tcindex pass index 42
in case the kernel was unable to run the last command (e.g. because of
the impossibility to load 'act_meta_skbtcindex'). For a similar reason,
the kernel can leak idr in the error path of tcf_ife_init(), because
tcf_idr_release() is not called after successful idr reservation:
# $TC actions add action ife encode allow tcindex index 47
IFE type 0xED3E
RTNETLINK answers: No such file or directory
We have an error talking to the kernel
# $TC actions add action ife encode allow tcindex index 47
IFE type 0xED3E
RTNETLINK answers: No space left on device
We have an error talking to the kernel
# $TC actions add action ife encode use mark 7 type 0xfefe pass index 47
IFE type 0xFEFE
RTNETLINK answers: No space left on device
We have an error talking to the kernel
Since tcfa_lock is already taken when the action is being edited, a call
to tcf_idr_release() wrongly makes tcf_idr_cleanup() take the same lock
again. On the other hand, tcf_idr_release() needs to be called in the
error path of tcf_ife_init(), to undo the last tcf_idr_create() invocation.
Fix both problems in tcf_ife_init().
Since the cleanup() routine can now be called when ife->params is NULL,
also add a NULL pointer check to avoid calling kfree_rcu(NULL, rcu).
[1]
============================================
WARNING: possible recursive locking detected
4.17.0-rc4.kasan+ #417 Tainted: G E
--------------------------------------------
tc/3932 is trying to acquire lock:
000000005097c9a6 (&(&p->tcfa_lock)->rlock){+...}, at: tcf_ife_cleanup+0x19/0x80 [act_ife]
but task is already holding lock:
000000005097c9a6 (&(&p->tcfa_lock)->rlock){+...}, at: tcf_ife_init+0xf6d/0x13c0 [act_ife]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(&p->tcfa_lock)->rlock);
lock(&(&p->tcfa_lock)->rlock);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by tc/3932:
#0: 000000007ca8e990 (rtnl_mutex){+.+.}, at: tcf_ife_init+0xf61/0x13c0 [act_ife]
#1: 000000005097c9a6 (&(&p->tcfa_lock)->rlock){+...}, at: tcf_ife_init+0xf6d/0x13c0 [act_ife]
stack backtrace:
CPU: 3 PID: 3932 Comm: tc Tainted: G E 4.17.0-rc4.kasan+ #417
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
Call Trace:
dump_stack+0x9a/0xeb
__lock_acquire+0xf43/0x34a0
? debug_check_no_locks_freed+0x2b0/0x2b0
? debug_check_no_locks_freed+0x2b0/0x2b0
? debug_check_no_locks_freed+0x2b0/0x2b0
? __mutex_lock+0x62f/0x1240
? kvm_sched_clock_read+0x1a/0x30
? sched_clock+0x5/0x10
? sched_clock_cpu+0x18/0x170
? find_held_lock+0x39/0x1d0
? lock_acquire+0x10b/0x330
lock_acquire+0x10b/0x330
? tcf_ife_cleanup+0x19/0x80 [act_ife]
_raw_spin_lock_bh+0x38/0x70
? tcf_ife_cleanup+0x19/0x80 [act_ife]
tcf_ife_cleanup+0x19/0x80 [act_ife]
__tcf_idr_release+0xff/0x350
tcf_ife_init+0xdde/0x13c0 [act_ife]
? ife_exit_net+0x290/0x290 [act_ife]
? __lock_is_held+0xb4/0x140
tcf_action_init_1+0x67b/0xad0
? tcf_action_dump_old+0xa0/0xa0
? sched_clock+0x5/0x10
? sched_clock_cpu+0x18/0x170
? kvm_sched_clock_read+0x1a/0x30
? sched_clock+0x5/0x10
? sched_clock_cpu+0x18/0x170
? memset+0x1f/0x40
tcf_action_init+0x30f/0x590
? tcf_action_init_1+0xad0/0xad0
? memset+0x1f/0x40
tc_ctl_action+0x48e/0x5e0
? mutex_lock_io_nested+0x1160/0x1160
? tca_action_gd+0x990/0x990
? sched_clock+0x5/0x10
? find_held_lock+0x39/0x1d0
rtnetlink_rcv_msg+0x4da/0x990
? validate_linkmsg+0x680/0x680
? sched_clock_cpu+0x18/0x170
? find_held_lock+0x39/0x1d0
netlink_rcv_skb+0x127/0x350
? validate_linkmsg+0x680/0x680
? netlink_ack+0x970/0x970
? __kmalloc_node_track_caller+0x304/0x3a0
netlink_unicast+0x40f/0x5d0
? netlink_attachskb+0x580/0x580
? _copy_from_iter_full+0x187/0x760
? import_iovec+0x90/0x390
netlink_sendmsg+0x67f/0xb50
? netlink_unicast+0x5d0/0x5d0
? copy_msghdr_from_user+0x206/0x340
? netlink_unicast+0x5d0/0x5d0
sock_sendmsg+0xb3/0xf0
___sys_sendmsg+0x60a/0x8b0
? copy_msghdr_from_user+0x340/0x340
? lock_downgrade+0x5e0/0x5e0
? tty_write_lock+0x18/0x50
? kvm_sched_clock_read+0x1a/0x30
? sched_clock+0x5/0x10
? sched_clock_cpu+0x18/0x170
? find_held_lock+0x39/0x1d0
? lock_downgrade+0x5e0/0x5e0
? lock_acquire+0x10b/0x330
? __audit_syscall_entry+0x316/0x690
? current_kernel_time64+0x6b/0xd0
? __fget_light+0x55/0x1f0
? __sys_sendmsg+0xd2/0x170
__sys_sendmsg+0xd2/0x170
? __ia32_sys_shutdown+0x70/0x70
? syscall_trace_enter+0x57a/0xd60
? rcu_read_lock_sched_held+0xdc/0x110
? __bpf_trace_sys_enter+0x10/0x10
? do_syscall_64+0x22/0x480
do_syscall_64+0xa5/0x480
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fd646988ba0
RSP: 002b:00007fffc9fab3c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fffc9fab4f0 RCX: 00007fd646988ba0
RDX: 0000000000000000 RSI: 00007fffc9fab440 RDI: 0000000000000003
RBP: 000000005b28c8b3 R08: 0000000000000002 R09: 0000000000000000
R10: 00007fffc9faae20 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffc9fab504 R14: 0000000000000001 R15: 000000000066c100
Fixes: 4e8c86155010 ("net sched: net sched: ife action fix late binding")
Fixes: ef6980b6becb ("introduce IFE action")
Signed-off-by: Davide Caratti <dcaratti@...hat.com>
---
net/sched/act_ife.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/net/sched/act_ife.c b/net/sched/act_ife.c
index 8527cfdc446d..078d52212172 100644
--- a/net/sched/act_ife.c
+++ b/net/sched/act_ife.c
@@ -415,7 +415,8 @@ static void tcf_ife_cleanup(struct tc_action *a)
spin_unlock_bh(&ife->tcf_lock);
p = rcu_dereference_protected(ife->params, 1);
- kfree_rcu(p, rcu);
+ if (p)
+ kfree_rcu(p, rcu);
}
/* under ife->tcf_lock for existing action */
@@ -543,10 +544,8 @@ static int tcf_ife_init(struct net *net, struct nlattr *nla,
NULL, NULL);
if (err) {
metadata_parse_err:
- if (exists)
- tcf_idr_release(*a, bind);
if (ret == ACT_P_CREATED)
- _tcf_ife_cleanup(*a);
+ tcf_idr_release(*a, bind);
if (exists)
spin_unlock_bh(&ife->tcf_lock);
@@ -567,7 +566,7 @@ static int tcf_ife_init(struct net *net, struct nlattr *nla,
err = use_all_metadata(ife);
if (err) {
if (ret == ACT_P_CREATED)
- _tcf_ife_cleanup(*a);
+ tcf_idr_release(*a, bind);
if (exists)
spin_unlock_bh(&ife->tcf_lock);
--
2.17.1
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