[PATCH 5.10 078/116] veth: fix races around rq->rx_notify_masked

Greg Kroah-Hartman
2022-02-14T09:54:26Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 68468d8c4cd4222a4ca1f185ab5a1c14480d078c ]

veth being NETIF_F_LLTX enabled, we need to be more careful
whenever we read/write rq->rx_notify_masked.

BUG: KCSAN: data-race in veth_xmit / veth_xmit

write to 0xffff888133d9a9f8 of 1 bytes by task 23552 on cpu 0:
__veth_xdp_flush drivers/net/veth.c:269 [inline]
veth_xmit+0x307/0x470 drivers/net/veth.c:350
__netdev_start_xmit include/linux/netdevice.h:4683 [inline]
netdev_start_xmit include/linux/netdevice.h:4697 [inline]
xmit_one+0x105/0x2f0 net/core/dev.c:3473
dev_hard_start_xmit net/core/dev.c:3489 [inline]
__dev_queue_xmit+0x86d/0xf90 net/core/dev.c:4116
dev_queue_xmit+0x13/0x20 net/core/dev.c:4149
br_dev_queue_push_xmit+0x3ce/0x430 net/bridge/br_forward.c:53
NF_HOOK include/linux/netfilter.h:307 [inline]
br_forward_finish net/bridge/br_forward.c:66 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
__br_forward+0x2e4/0x400 net/bridge/br_forward.c:115
br_flood+0x521/0x5c0 net/bridge/br_forward.c:242
br_dev_xmit+0x8b6/0x960
__netdev_start_xmit include/linux/netdevice.h:4683 [inline]
netdev_start_xmit include/linux/netdevice.h:4697 [inline]
xmit_one+0x105/0x2f0 net/core/dev.c:3473
dev_hard_start_xmit net/core/dev.c:3489 [inline]
__dev_queue_xmit+0x86d/0xf90 net/core/dev.c:4116
dev_queue_xmit+0x13/0x20 net/core/dev.c:4149
neigh_hh_output include/net/neighbour.h:525 [inline]
neigh_output include/net/neighbour.h:539 [inline]
ip_finish_output2+0x6f8/0xb70 net/ipv4/ip_output.c:228
ip_finish_output+0xfb/0x240 net/ipv4/ip_output.c:316
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip_output+0xf3/0x1a0 net/ipv4/ip_output.c:430
dst_output include/net/dst.h:451 [inline]
ip_local_out net/ipv4/ip_output.c:126 [inline]
ip_send_skb+0x6e/0xe0 net/ipv4/ip_output.c:1570
udp_send_skb+0x641/0x880 net/ipv4/udp.c:967
udp_sendmsg+0x12ea/0x14c0 net/ipv4/udp.c:1254
inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:819
sock_sendmsg_nosec net/socket.c:705 [inline]
sock_sendmsg net/socket.c:725 [inline]
____sys_sendmsg+0x39a/0x510 net/socket.c:2413
___sys_sendmsg net/socket.c:2467 [inline]
__sys_sendmmsg+0x267/0x4c0 net/socket.c:2553
__do_sys_sendmmsg net/socket.c:2582 [inline]
__se_sys_sendmmsg net/socket.c:2579 [inline]
__x64_sys_sendmmsg+0x53/0x60 net/socket.c:2579
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888133d9a9f8 of 1 bytes by task 23563 on cpu 1:
__veth_xdp_flush drivers/net/veth.c:268 [inline]
veth_xmit+0x2d6/0x470 drivers/net/veth.c:350
__netdev_start_xmit include/linux/netdevice.h:4683 [inline]
netdev_start_xmit include/linux/netdevice.h:4697 [inline]
xmit_one+0x105/0x2f0 net/core/dev.c:3473
dev_hard_start_xmit net/core/dev.c:3489 [inline]
__dev_queue_xmit+0x86d/0xf90 net/core/dev.c:4116
dev_queue_xmit+0x13/0x20 net/core/dev.c:4149
br_dev_queue_push_xmit+0x3ce/0x430 net/bridge/br_forward.c:53
NF_HOOK include/linux/netfilter.h:307 [inline]
br_forward_finish net/bridge/br_forward.c:66 [inline]
NF_HOOK include/linux/netfilter.h:307 [inline]
__br_forward+0x2e4/0x400 net/bridge/br_forward.c:115
br_flood+0x521/0x5c0 net/bridge/br_forward.c:242
br_dev_xmit+0x8b6/0x960
__netdev_start_xmit include/linux/netdevice.h:4683 [inline]
netdev_start_xmit include/linux/netdevice.h:4697 [inline]
xmit_one+0x105/0x2f0 net/core/dev.c:3473
dev_hard_start_xmit net/core/dev.c:3489 [inline]
__dev_queue_xmit+0x86d/0xf90 net/core/dev.c:4116
dev_queue_xmit+0x13/0x20 net/core/dev.c:4149
neigh_hh_output include/net/neighbour.h:525 [inline]
neigh_output include/net/neighbour.h:539 [inline]
ip_finish_output2+0x6f8/0xb70 net/ipv4/ip_output.c:228
ip_finish_output+0xfb/0x240 net/ipv4/ip_output.c:316
NF_HOOK_COND include/linux/netfilter.h:296 [inline]
ip_output+0xf3/0x1a0 net/ipv4/ip_output.c:430
dst_output include/net/dst.h:451 [inline]
ip_local_out net/ipv4/ip_output.c:126 [inline]
ip_send_skb+0x6e/0xe0 net/ipv4/ip_output.c:1570
udp_send_skb+0x641/0x880 net/ipv4/udp.c:967
udp_sendmsg+0x12ea/0x14c0 net/ipv4/udp.c:1254
inet_sendmsg+0x5f/0x80 net/ipv4/af_inet.c:819
sock_sendmsg_nosec net/socket.c:705 [inline]
sock_sendmsg net/socket.c:725 [inline]
____sys_sendmsg+0x39a/0x510 net/socket.c:2413
___sys_sendmsg net/socket.c:2467 [inline]
__sys_sendmmsg+0x267/0x4c0 net/socket.c:2553
__do_sys_sendmmsg net/socket.c:2582 [inline]
__se_sys_sendmmsg net/socket.c:2579 [inline]
__x64_sys_sendmmsg+0x53/0x60 net/socket.c:2579
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23563 Comm: syz-executor.5 Not tainted 5.17.0-rc2-syzkaller-00064-gc36c04c2e132 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

Fixes: 948d4f214fde ("veth: Add driver XDP")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/veth.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index aef66f8eecee1..f7e3eb309a26e 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -256,9 +256,10 @@ static void __veth_xdp_flush(struct veth_rq *rq)
{
/* Write ptr_ring before reading rx_notify_masked */
smp_mb();
- if (!rq->rx_notify_masked) {
- rq->rx_notify_masked = true;
- napi_schedule(&rq->xdp_napi);
+ if (!READ_ONCE(rq->rx_notify_masked) &&
+ napi_schedule_prep(&rq->xdp_napi)) {
+ WRITE_ONCE(rq->rx_notify_masked, true);
+ __napi_schedule(&rq->xdp_napi);
}
}

@@ -852,8 +853,10 @@ static int veth_poll(struct napi_struct *napi, int budget)
/* Write rx_notify_masked before reading ptr_ring */
smp_store_mb(rq->rx_notify_masked, false);
if (unlikely(!__ptr_ring_empty(&rq->xdp_ring))) {
- rq->rx_notify_masked = true;
- napi_schedule(&rq->xdp_napi);
+ if (napi_schedule_prep(&rq->xdp_napi)) {
+ WRITE_ONCE(rq->rx_notify_masked, true);
+ __napi_schedule(&rq->xdp_napi);
+ }
}
}

--
2.34.1