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authorEric Dumazet <edumazet@google.com>2023-01-20 12:59:53 +0000
committerJakub Kicinski <kuba@kernel.org>2023-01-23 21:35:53 -0800
commitc1bb9484e3b05166880da8574504156ccbd0549e (patch)
treef10462378b48ae1f238eaf3c755853cfd4c7b1e7 /net
parent9f535c870e493841ac7be390610ff2edec755762 (diff)
netlink: annotate data races around nlk->portid
syzbot reminds us netlink_getname() runs locklessly [1] This first patch annotates the race against nlk->portid. Following patches take care of the remaining races. [1] BUG: KCSAN: data-race in netlink_getname / netlink_insert write to 0xffff88814176d310 of 4 bytes by task 2315 on cpu 1: netlink_insert+0xf1/0x9a0 net/netlink/af_netlink.c:583 netlink_autobind+0xae/0x180 net/netlink/af_netlink.c:856 netlink_sendmsg+0x444/0x760 net/netlink/af_netlink.c:1895 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0x38f/0x500 net/socket.c:2476 ___sys_sendmsg net/socket.c:2530 [inline] __sys_sendmsg+0x19a/0x230 net/socket.c:2559 __do_sys_sendmsg net/socket.c:2568 [inline] __se_sys_sendmsg net/socket.c:2566 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2566 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd read to 0xffff88814176d310 of 4 bytes by task 2316 on cpu 0: netlink_getname+0xcd/0x1a0 net/netlink/af_netlink.c:1144 __sys_getsockname+0x11d/0x1b0 net/socket.c:2026 __do_sys_getsockname net/socket.c:2041 [inline] __se_sys_getsockname net/socket.c:2038 [inline] __x64_sys_getsockname+0x3e/0x50 net/socket.c:2038 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd value changed: 0x00000000 -> 0xc9a49780 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 2316 Comm: syz-executor.2 Not tainted 6.2.0-rc3-syzkaller-00030-ge8f60cd7db24-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/netlink/af_netlink.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index bca2a470ccad..4aea89f7d700 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -580,7 +580,9 @@ static int netlink_insert(struct sock *sk, u32 portid)
if (nlk_sk(sk)->bound)
goto err;
- nlk_sk(sk)->portid = portid;
+ /* portid can be read locklessly from netlink_getname(). */
+ WRITE_ONCE(nlk_sk(sk)->portid, portid);
+
sock_hold(sk);
err = __netlink_insert(table, sk);
@@ -1141,7 +1143,8 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr,
nladdr->nl_pid = nlk->dst_portid;
nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
} else {
- nladdr->nl_pid = nlk->portid;
+ /* Paired with WRITE_ONCE() in netlink_insert() */
+ nladdr->nl_pid = READ_ONCE(nlk->portid);
netlink_lock_table();
nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
netlink_unlock_table();