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authorEric Dumazet <edumazet@google.com>2019-10-14 20:22:30 +0200
committerDavid S. Miller <davem@davemloft.net>2019-10-16 05:20:22 +0200
commit39f13ea2f61b439ebe0060393e9c39925c9ee28c (patch)
tree7de52bb550007010a18981bb8e0d04633c984508 /net
parentnet: dsa: sja1105: Use the correct style for SPDX License Identifier (diff)
downloadlinux-39f13ea2f61b439ebe0060393e9c39925c9ee28c.tar.xz
linux-39f13ea2f61b439ebe0060393e9c39925c9ee28c.zip
net: avoid potential infinite loop in tc_ctl_action()
tc_ctl_action() has the ability to loop forever if tcf_action_add() returns -EAGAIN. This special case has been done in case a module needed to be loaded, but it turns out that tcf_add_notify() could also return -EAGAIN if the socket sk_rcvbuf limit is hit. We need to separate the two cases, and only loop for the module loading case. While we are at it, add a limit of 10 attempts since unbounded loops are always scary. syzbot repro was something like : socket(PF_NETLINK, SOCK_RAW|SOCK_NONBLOCK, NETLINK_ROUTE) = 3 write(3, ..., 38) = 38 setsockopt(3, SOL_SOCKET, SO_RCVBUF, [0], 4) = 0 sendmsg(3, {msg_name(0)=NULL, msg_iov(1)=[{..., 388}], msg_controllen=0, msg_flags=0x10}, ...) NMI backtrace for cpu 0 CPU: 0 PID: 1054 Comm: khungtaskd Not tainted 5.4.0-rc1+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0x9d0/0xef0 kernel/hung_task.c:289 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 8859 Comm: syz-executor910 Not tainted 5.4.0-rc1+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:arch_local_save_flags arch/x86/include/asm/paravirt.h:751 [inline] RIP: 0010:lockdep_hardirqs_off+0x1df/0x2e0 kernel/locking/lockdep.c:3453 Code: 5c 08 00 00 5b 41 5c 41 5d 5d c3 48 c7 c0 58 1d f3 88 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 0f 85 d3 00 00 00 <48> 83 3d 21 9e 99 07 00 0f 84 b9 00 00 00 9c 58 0f 1f 44 00 00 f6 RSP: 0018:ffff8880a6f3f1b8 EFLAGS: 00000046 RAX: 1ffffffff11e63ab RBX: ffff88808c9c6080 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffff88808c9c6914 RBP: ffff8880a6f3f1d0 R08: ffff88808c9c6080 R09: fffffbfff16be5d1 R10: fffffbfff16be5d0 R11: 0000000000000003 R12: ffffffff8746591f R13: ffff88808c9c6080 R14: ffffffff8746591f R15: 0000000000000003 FS: 00000000011e4880(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000000a8920000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: trace_hardirqs_off+0x62/0x240 kernel/trace/trace_preemptirq.c:45 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline] _raw_spin_lock_irqsave+0x6f/0xcd kernel/locking/spinlock.c:159 __wake_up_common_lock+0xc8/0x150 kernel/sched/wait.c:122 __wake_up+0xe/0x10 kernel/sched/wait.c:142 netlink_unlock_table net/netlink/af_netlink.c:466 [inline] netlink_unlock_table net/netlink/af_netlink.c:463 [inline] netlink_broadcast_filtered+0x705/0xb80 net/netlink/af_netlink.c:1514 netlink_broadcast+0x3a/0x50 net/netlink/af_netlink.c:1534 rtnetlink_send+0xdd/0x110 net/core/rtnetlink.c:714 tcf_add_notify net/sched/act_api.c:1343 [inline] tcf_action_add+0x243/0x370 net/sched/act_api.c:1362 tc_ctl_action+0x3b5/0x4bc net/sched/act_api.c:1410 rtnetlink_rcv_msg+0x463/0xb00 net/core/rtnetlink.c:5386 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477 rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5404 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline] netlink_unicast+0x531/0x710 net/netlink/af_netlink.c:1328 netlink_sendmsg+0x8a5/0xd60 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:637 [inline] sock_sendmsg+0xd7/0x130 net/socket.c:657 ___sys_sendmsg+0x803/0x920 net/socket.c:2311 __sys_sendmsg+0x105/0x1d0 net/socket.c:2356 __do_sys_sendmsg net/socket.c:2365 [inline] __se_sys_sendmsg net/socket.c:2363 [inline] __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2363 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x440939 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot+cf0adbb9c28c8866c788@syzkaller.appspotmail.com Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/sched/act_api.c14
1 files changed, 8 insertions, 6 deletions
diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 4e7429c6f864..69d4676a402f 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -1353,11 +1353,16 @@ static int tcf_action_add(struct net *net, struct nlattr *nla,
struct netlink_ext_ack *extack)
{
size_t attr_size = 0;
- int ret = 0;
+ int loop, ret;
struct tc_action *actions[TCA_ACT_MAX_PRIO] = {};
- ret = tcf_action_init(net, NULL, nla, NULL, NULL, ovr, 0, actions,
- &attr_size, true, extack);
+ for (loop = 0; loop < 10; loop++) {
+ ret = tcf_action_init(net, NULL, nla, NULL, NULL, ovr, 0,
+ actions, &attr_size, true, extack);
+ if (ret != -EAGAIN)
+ break;
+ }
+
if (ret < 0)
return ret;
ret = tcf_add_notify(net, n, actions, portid, attr_size, extack);
@@ -1407,11 +1412,8 @@ static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,
*/
if (n->nlmsg_flags & NLM_F_REPLACE)
ovr = 1;
-replay:
ret = tcf_action_add(net, tca[TCA_ACT_TAB], n, portid, ovr,
extack);
- if (ret == -EAGAIN)
- goto replay;
break;
case RTM_DELACTION:
ret = tca_action_gd(net, tca[TCA_ACT_TAB], n,