6.6-stable review patch. If anyone has any objections, please let me know.
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From: Shigeru Yoshida syoshida@redhat.com
[ Upstream commit 4cd12c6065dfcdeba10f49949bffcf383b3952d8 ]
syzbot reported the following NULL pointer dereference issue [1]:
BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] RIP: 0010:0x0 [...] Call Trace: <TASK> sk_psock_verdict_data_ready+0x232/0x340 net/core/skmsg.c:1230 unix_stream_sendmsg+0x9b4/0x1230 net/unix/af_unix.c:2293 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77
If sk_psock_verdict_data_ready() and sk_psock_stop_verdict() are called concurrently, psock->saved_data_ready can be NULL, causing the above issue.
This patch fixes this issue by calling the appropriate data ready function using the sk_psock_data_ready() helper and protecting it from concurrency with sk->sk_callback_lock.
Fixes: 6df7f764cd3c ("bpf, sockmap: Wake up polling after data copy") Reported-by: syzbot+fd7b34375c1c8ce29c93@syzkaller.appspotmail.com Signed-off-by: Shigeru Yoshida syoshida@redhat.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Tested-by: syzbot+fd7b34375c1c8ce29c93@syzkaller.appspotmail.com Acked-by: John Fastabend john.fastabend@gmail.com Closes: https://syzkaller.appspot.com/bug?extid=fd7b34375c1c8ce29c93 [1] Link: https://lore.kernel.org/bpf/20240218150933.6004-1-syoshida@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/skmsg.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 93ecfceac1bc4..4d75ef9d24bfa 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -1226,8 +1226,11 @@ static void sk_psock_verdict_data_ready(struct sock *sk)
rcu_read_lock(); psock = sk_psock(sk); - if (psock) - psock->saved_data_ready(sk); + if (psock) { + read_lock_bh(&sk->sk_callback_lock); + sk_psock_data_ready(sk, psock); + read_unlock_bh(&sk->sk_callback_lock); + } rcu_read_unlock(); } }