From: Stefano Garzarella <sgarzare@redhat.com>
To: davem@davemloft.net
Cc: Jorgen Hansen <jhansen@vmware.com>,
Stefano Garzarella <sgarzare@redhat.com>,
netdev@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
Dexuan Cui <decui@microsoft.com>,
linux-kernel@vger.kernel.org,
Stefan Hajnoczi <stefanha@redhat.com>
Subject: [PATCH net 1/2] vsock: fix potential null pointer dereference in vsock_poll()
Date: Tue, 11 Aug 2020 11:55:03 +0200 [thread overview]
Message-ID: <20200811095504.25051-2-sgarzare@redhat.com> (raw)
In-Reply-To: <20200811095504.25051-1-sgarzare@redhat.com>
syzbot reported this issue where in the vsock_poll() we find the
socket state at TCP_ESTABLISHED, but 'transport' is null:
general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097]
CPU: 0 PID: 8227 Comm: syz-executor.2 Not tainted 5.8.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:vsock_poll+0x75a/0x8e0 net/vmw_vsock/af_vsock.c:1038
Call Trace:
sock_poll+0x159/0x460 net/socket.c:1266
vfs_poll include/linux/poll.h:90 [inline]
do_pollfd fs/select.c:869 [inline]
do_poll fs/select.c:917 [inline]
do_sys_poll+0x607/0xd40 fs/select.c:1011
__do_sys_poll fs/select.c:1069 [inline]
__se_sys_poll fs/select.c:1057 [inline]
__x64_sys_poll+0x18c/0x440 fs/select.c:1057
do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
entry_SYSCALL_64_after_hwframe+0x44/0xa9
This issue can happen if the TCP_ESTABLISHED state is set after we read
the vsk->transport in the vsock_poll().
We could put barriers to synchronize, but this can only happen during
connection setup, so we can simply check that 'transport' is valid.
Fixes: c0cfa2d8a788 ("vsock: add multi-transports support")
Reported-and-tested-by: syzbot+a61bac2fcc1a7c6623fe@syzkaller.appspotmail.com
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---
net/vmw_vsock/af_vsock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 27bbcfad9c17..9e93bc201cc0 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1032,7 +1032,7 @@ static __poll_t vsock_poll(struct file *file, struct socket *sock,
}
/* Connected sockets that can produce data can be written. */
- if (sk->sk_state == TCP_ESTABLISHED) {
+ if (transport && sk->sk_state == TCP_ESTABLISHED) {
if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
bool space_avail_now = false;
int ret = transport->notify_poll_out(
--
2.26.2
next prev parent reply other threads:[~2020-08-11 9:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-11 9:55 [PATCH net 0/2] vsock: fix null pointer dereference and cleanup in vsock_poll() Stefano Garzarella
2020-08-11 9:55 ` Stefano Garzarella [this message]
2020-08-11 9:55 ` [PATCH net 2/2] vsock: small " Stefano Garzarella
2020-08-11 17:24 ` [PATCH net 0/2] vsock: fix null pointer dereference and " David Miller
2020-08-12 7:17 ` Stefano Garzarella
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