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Message-ID: <1518586684-12307-8-git-send-email-ying.xue@windriver.com>
Date: Wed, 14 Feb 2018 13:38:04 +0800
From: Ying Xue <ying.xue@...driver.com>
To: <davem@...emloft.net>, <ktkhai@...tuozzo.com>,
<jon.maloy@...csson.com>
CC: <netdev@...r.kernel.org>, <syzkaller-bugs@...glegroups.com>,
<tipc-discussion@...ts.sourceforge.net>
Subject: [PATCH net v4 7/7] tipc: Fix missing RTNL lock protection during setting link properties
Currently when user changes link properties, TIPC first checks if
user's command message contains media name or bearer name through
tipc_media_find() or tipc_bearer_find() which is protected by RTNL
lock. But when tipc_nl_compat_link_set() conducts the checking with
the two functions, it doesn't hold RTNL lock at all, as a result,
the following complaints were reported:
audit: type=1400 audit(1514679888.244:9): avc: denied { write } for
pid=3194 comm="syzkaller021477" path="socket:[11143]" dev="sockfs"
ino=11143 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
tclass=netlink_generic_socket permissive=1
=============================
WARNING: suspicious RCU usage
4.15.0-rc5+ #152 Not tainted
-----------------------------
net/tipc/bearer.c:177 suspicious rcu_dereference_protected() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
2 locks held by syzkaller021477/3194:
#0: (cb_lock){++++}, at: [<00000000d20133ea>] genl_rcv+0x19/0x40
net/netlink/genetlink.c:634
#1: (genl_mutex){+.+.}, at: [<00000000fcc5d1bc>] genl_lock
net/netlink/genetlink.c:33 [inline]
#1: (genl_mutex){+.+.}, at: [<00000000fcc5d1bc>] genl_rcv_msg+0x115/0x140
net/netlink/genetlink.c:622
stack backtrace:
CPU: 1 PID: 3194 Comm: syzkaller021477 Not tainted 4.15.0-rc5+ #152
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
lockdep_rcu_suspicious+0x123/0x170 kernel/locking/lockdep.c:4585
tipc_bearer_find+0x2b4/0x3b0 net/tipc/bearer.c:177
tipc_nl_compat_link_set+0x329/0x9f0 net/tipc/netlink_compat.c:729
__tipc_nl_compat_doit net/tipc/netlink_compat.c:288 [inline]
tipc_nl_compat_doit+0x15b/0x660 net/tipc/netlink_compat.c:335
tipc_nl_compat_handle net/tipc/netlink_compat.c:1119 [inline]
tipc_nl_compat_recv+0x112f/0x18f0 net/tipc/netlink_compat.c:1201
genl_family_rcv_msg+0x7b7/0xfb0 net/netlink/genetlink.c:599
genl_rcv_msg+0xb2/0x140 net/netlink/genetlink.c:624
netlink_rcv_skb+0x21e/0x460 net/netlink/af_netlink.c:2408
genl_rcv+0x28/0x40 net/netlink/genetlink.c:635
netlink_unicast_kernel net/netlink/af_netlink.c:1275 [inline]
netlink_unicast+0x4e8/0x6f0 net/netlink/af_netlink.c:1301
netlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1864
sock_sendmsg_nosec net/socket.c:636 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:646
sock_write_iter+0x31a/0x5d0 net/socket.c:915
call_write_iter include/linux/fs.h:1772 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x684/0x970 fs/read_write.c:482
vfs_write+0x189/0x510 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xef/0x220 fs/read_write.c:581
do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129
In order to correct the mistake, __tipc_nl_compat_doit() has been
protected by RTNL lock, which means the whole operation of setting
bearer/media properties is under RTNL protection.
Signed-off-by: Ying Xue <ying.xue@...driver.com>
Reported-by: syzbot <syzbot+6345fd433db009b29413@...kaller.appspotmail.com>
---
net/tipc/netlink_compat.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index 9741690..4492cda 100644
--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -301,6 +301,7 @@ static int __tipc_nl_compat_doit(struct tipc_nl_compat_cmd_doit *cmd,
memset(&info, 0, sizeof(info));
info.attrs = attrbuf;
+ rtnl_lock();
err = (*cmd->transcode)(cmd, trans_buf, msg);
if (err)
goto doit_out;
@@ -315,6 +316,7 @@ static int __tipc_nl_compat_doit(struct tipc_nl_compat_cmd_doit *cmd,
err = (*cmd->doit)(doit_buf, &info);
doit_out:
+ rtnl_unlock();
kfree_skb(doit_buf);
attrbuf_out:
@@ -723,13 +725,13 @@ static int tipc_nl_compat_link_set(struct tipc_nl_compat_cmd_doit *cmd,
media = tipc_media_find(lc->name);
if (media) {
- cmd->doit = &tipc_nl_media_set;
+ cmd->doit = &__tipc_nl_media_set;
return tipc_nl_compat_media_set(skb, msg);
}
bearer = tipc_bearer_find(msg->net, lc->name);
if (bearer) {
- cmd->doit = &tipc_nl_bearer_set;
+ cmd->doit = &__tipc_nl_bearer_set;
return tipc_nl_compat_bearer_set(skb, msg);
}
@@ -1090,12 +1092,12 @@ static int tipc_nl_compat_handle(struct tipc_nl_compat_msg *msg)
return tipc_nl_compat_dumpit(&dump, msg);
case TIPC_CMD_ENABLE_BEARER:
msg->req_type = TIPC_TLV_BEARER_CONFIG;
- doit.doit = tipc_nl_bearer_enable;
+ doit.doit = __tipc_nl_bearer_enable;
doit.transcode = tipc_nl_compat_bearer_enable;
return tipc_nl_compat_doit(&doit, msg);
case TIPC_CMD_DISABLE_BEARER:
msg->req_type = TIPC_TLV_BEARER_NAME;
- doit.doit = tipc_nl_bearer_disable;
+ doit.doit = __tipc_nl_bearer_disable;
doit.transcode = tipc_nl_compat_bearer_disable;
return tipc_nl_compat_doit(&doit, msg);
case TIPC_CMD_SHOW_LINK_STATS:
@@ -1149,12 +1151,12 @@ static int tipc_nl_compat_handle(struct tipc_nl_compat_msg *msg)
return tipc_nl_compat_dumpit(&dump, msg);
case TIPC_CMD_SET_NODE_ADDR:
msg->req_type = TIPC_TLV_NET_ADDR;
- doit.doit = tipc_nl_net_set;
+ doit.doit = __tipc_nl_net_set;
doit.transcode = tipc_nl_compat_net_set;
return tipc_nl_compat_doit(&doit, msg);
case TIPC_CMD_SET_NETID:
msg->req_type = TIPC_TLV_UNSIGNED;
- doit.doit = tipc_nl_net_set;
+ doit.doit = __tipc_nl_net_set;
doit.transcode = tipc_nl_compat_net_set;
return tipc_nl_compat_doit(&doit, msg);
case TIPC_CMD_GET_NETID:
--
2.7.4
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