This is a note to let you know that I've just added the patch titled
bonding: fix missed rcu protection
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bonding-fix-missed-rcu-protection.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 92743cdb6539baed6a9ede70b8a64b1fee96f354
Author: Hangbin Liu <liuhangbin@xxxxxxxxx>
Date: Thu May 19 10:01:48 2022 +0800
bonding: fix missed rcu protection
[ Upstream commit 9b80ccda233fa6c59de411bf889cc4d0e028f2c7 ]
When removing the rcu_read_lock in bond_ethtool_get_ts_info() as
discussed [1], I didn't notice it could be called via setsockopt,
which doesn't hold rcu lock, as syzbot pointed:
stack backtrace:
CPU: 0 PID: 3599 Comm: syz-executor317 Not tainted 5.18.0-rc5-syzkaller-01392-g01f4685797a5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
bond_option_active_slave_get_rcu include/net/bonding.h:353 [inline]
bond_ethtool_get_ts_info+0x32c/0x3a0 drivers/net/bonding/bond_main.c:5595
__ethtool_get_ts_info+0x173/0x240 net/ethtool/common.c:554
ethtool_get_phc_vclocks+0x99/0x110 net/ethtool/common.c:568
sock_timestamping_bind_phc net/core/sock.c:869 [inline]
sock_set_timestamping+0x3a3/0x7e0 net/core/sock.c:916
sock_setsockopt+0x543/0x2ec0 net/core/sock.c:1221
__sys_setsockopt+0x55e/0x6a0 net/socket.c:2223
__do_sys_setsockopt net/socket.c:2238 [inline]
__se_sys_setsockopt net/socket.c:2235 [inline]
__x64_sys_setsockopt+0xba/0x150 net/socket.c:2235
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f8902c8eb39
Fix it by adding rcu_read_lock and take a ref on the real_dev.
Since dev_hold() and dev_put() can take NULL these days, we can
skip checking if real_dev exist.
[1] https://lore.kernel.org/netdev/27565.1642742439@famine/
Reported-by: syzbot+92beb3d46aab498710fa@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: aa6034678e87 ("bonding: use rcu_dereference_rtnl when get bonding active slave")
Suggested-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Hangbin Liu <liuhangbin@xxxxxxxxx>
Reviewed-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
Link: https://lore.kernel.org/r/20220519020148.1058344-1-liuhangbin@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 38e152548126..b5c5196e03ee 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -5591,16 +5591,23 @@ static int bond_ethtool_get_ts_info(struct net_device *bond_dev,
const struct ethtool_ops *ops;
struct net_device *real_dev;
struct phy_device *phydev;
+ int ret = 0;
+ rcu_read_lock();
real_dev = bond_option_active_slave_get_rcu(bond);
+ dev_hold(real_dev);
+ rcu_read_unlock();
+
if (real_dev) {
ops = real_dev->ethtool_ops;
phydev = real_dev->phydev;
if (phy_has_tsinfo(phydev)) {
- return phy_ts_info(phydev, info);
+ ret = phy_ts_info(phydev, info);
+ goto out;
} else if (ops->get_ts_info) {
- return ops->get_ts_info(real_dev, info);
+ ret = ops->get_ts_info(real_dev, info);
+ goto out;
}
}
@@ -5608,7 +5615,9 @@ static int bond_ethtool_get_ts_info(struct net_device *bond_dev,
SOF_TIMESTAMPING_SOFTWARE;
info->phc_index = -1;
- return 0;
+out:
+ dev_put(real_dev);
+ return ret;
}
static const struct ethtool_ops bond_ethtool_ops = {
