| From: Ilya Dryomov <idryomov@gmail.com> |
| Date: Tue, 24 Apr 2018 19:10:55 +0200 |
| Subject: libceph: validate con->state at the top of try_write() |
| |
| commit 9c55ad1c214d9f8c4594ac2c3fa392c1c32431a7 upstream. |
| |
| ceph_con_workfn() validates con->state before calling try_read() and |
| then try_write(). However, try_read() temporarily releases con->mutex, |
| notably in process_message() and ceph_con_in_msg_alloc(), opening the |
| window for ceph_con_close() to sneak in, close the connection and |
| release con->sock. When try_write() is called on the assumption that |
| con->state is still valid (i.e. not STANDBY or CLOSED), a NULL sock |
| gets passed to the networking stack: |
| |
| BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 |
| IP: selinux_socket_sendmsg+0x5/0x20 |
| |
| Make sure con->state is valid at the top of try_write() and add an |
| explicit BUG_ON for this, similar to try_read(). |
| |
| Link: https://tracker.ceph.com/issues/23706 |
| Signed-off-by: Ilya Dryomov <idryomov@gmail.com> |
| Reviewed-by: Jason Dillaman <dillaman@redhat.com> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| net/ceph/messenger.c | 7 +++++++ |
| 1 file changed, 7 insertions(+) |
| |
| --- a/net/ceph/messenger.c |
| +++ b/net/ceph/messenger.c |
| @@ -2453,6 +2453,11 @@ static int try_write(struct ceph_connect |
| int ret = 1; |
| |
| dout("try_write start %p state %lu\n", con, con->state); |
| + if (con->state != CON_STATE_PREOPEN && |
| + con->state != CON_STATE_CONNECTING && |
| + con->state != CON_STATE_NEGOTIATING && |
| + con->state != CON_STATE_OPEN) |
| + return 0; |
| |
| more: |
| dout("try_write out_kvec_bytes %d\n", con->out_kvec_bytes); |
| @@ -2478,6 +2483,8 @@ more: |
| } |
| |
| more_kvec: |
| + BUG_ON(!con->sock); |
| + |
| /* kvec data queued? */ |
| if (con->out_skip) { |
| ret = write_partial_skip(con); |