diff options
| author | Eric Dumazet <edumazet@google.com> | 2021-10-04 14:24:15 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-10-05 13:11:09 +0100 |
| commit | 7707a4d01a648e4c655101a469c956cb11273655 (patch) | |
| tree | 9cac68d55159db0676abea2e56460838c2fbaa54 /net/netlink | |
| parent | e3cf002d5a4452f8adc5543df341cf96fd702fcf (diff) | |
netlink: annotate data races around nlk->bound
While existing code is correct, KCSAN is reporting
a data-race in netlink_insert / netlink_sendmsg [1]
It is correct to read nlk->bound without a lock, as netlink_autobind()
will acquire all needed locks.
[1]
BUG: KCSAN: data-race in netlink_insert / netlink_sendmsg
write to 0xffff8881031c8b30 of 1 bytes by task 18752 on cpu 0:
netlink_insert+0x5cc/0x7f0 net/netlink/af_netlink.c:597
netlink_autobind+0xa9/0x150 net/netlink/af_netlink.c:842
netlink_sendmsg+0x479/0x7c0 net/netlink/af_netlink.c:1892
sock_sendmsg_nosec net/socket.c:703 [inline]
sock_sendmsg net/socket.c:723 [inline]
____sys_sendmsg+0x360/0x4d0 net/socket.c:2392
___sys_sendmsg net/socket.c:2446 [inline]
__sys_sendmsg+0x1ed/0x270 net/socket.c:2475
__do_sys_sendmsg net/socket.c:2484 [inline]
__se_sys_sendmsg net/socket.c:2482 [inline]
__x64_sys_sendmsg+0x42/0x50 net/socket.c:2482
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
read to 0xffff8881031c8b30 of 1 bytes by task 18751 on cpu 1:
netlink_sendmsg+0x270/0x7c0 net/netlink/af_netlink.c:1891
sock_sendmsg_nosec net/socket.c:703 [inline]
sock_sendmsg net/socket.c:723 [inline]
__sys_sendto+0x2a8/0x370 net/socket.c:2019
__do_sys_sendto net/socket.c:2031 [inline]
__se_sys_sendto net/socket.c:2027 [inline]
__x64_sys_sendto+0x74/0x90 net/socket.c:2027
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0x90 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: 18751 Comm: syz-executor.0 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Fixes: da314c9923fe ("netlink: Replace rhash_portid with bound")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netlink')
| -rw-r--r-- | net/netlink/af_netlink.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 24b7cf447bc5..ada47e59647a 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -594,7 +594,10 @@ static int netlink_insert(struct sock *sk, u32 portid) /* We need to ensure that the socket is hashed and visible. */ smp_wmb(); - nlk_sk(sk)->bound = portid; + /* Paired with lockless reads from netlink_bind(), + * netlink_connect() and netlink_sendmsg(). + */ + WRITE_ONCE(nlk_sk(sk)->bound, portid); err: release_sock(sk); @@ -1012,7 +1015,8 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, if (nlk->ngroups < BITS_PER_LONG) groups &= (1UL << nlk->ngroups) - 1; - bound = nlk->bound; + /* Paired with WRITE_ONCE() in netlink_insert() */ + bound = READ_ONCE(nlk->bound); if (bound) { /* Ensure nlk->portid is up-to-date. */ smp_rmb(); @@ -1098,8 +1102,9 @@ static int netlink_connect(struct socket *sock, struct sockaddr *addr, /* No need for barriers here as we return to user-space without * using any of the bound attributes. + * Paired with WRITE_ONCE() in netlink_insert(). */ - if (!nlk->bound) + if (!READ_ONCE(nlk->bound)) err = netlink_autobind(sock); if (err == 0) { @@ -1888,7 +1893,8 @@ static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) dst_group = nlk->dst_group; } - if (!nlk->bound) { + /* Paired with WRITE_ONCE() in netlink_insert() */ + if (!READ_ONCE(nlk->bound)) { err = netlink_autobind(sock); if (err) goto out; |