From: Stefano Garzarella <sgarz...@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+a61bac2fcc1a7c662...@syzkaller.appspotmail.com
Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
Reviewed-by: Jorgen Hansen <jhan...@vmware.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
https://jira.sw.ru/browse/PSBM-128702
(cherry picked from commit 1980c05844830a44708c98c96d600833aa3fae08)
Signed-off-by: Konstantin Khorenko <khore...@virtuozzo.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 cc69c6a2c4ef..c6e07531bdba 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -1033,7 +1033,7 @@ static unsigned int 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(
--
2.24.3
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