mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-11 13:04:03 +08:00
75dbb685f4
request_reinit() is not only ugly as the comment rightfully suggests,
but also unsafe. Even though it is called with osdc->lock held for
write in all cases, resetting the OSD request refcount can still race
with handle_reply() and result in use-after-free. Taking linger ping
as an example:
handle_timeout thread handle_reply thread
down_read(&osdc->lock)
req = lookup_request(...)
...
finish_request(req) # unregisters
up_read(&osdc->lock)
__complete_request(req)
linger_ping_cb(req)
# req->r_kref == 2 because handle_reply still holds its ref
down_write(&osdc->lock)
send_linger_ping(lreq)
req = lreq->ping_req # same req
# cancel_linger_request is NOT
# called - handle_reply already
# unregistered
request_reinit(req)
WARN_ON(req->r_kref != 1) # fires
request_init(req)
kref_init(req->r_kref)
# req->r_kref == 1 after kref_init
ceph_osdc_put_request(req)
kref_put(req->r_kref)
# req->r_kref == 0 after kref_put, req is freed
<further req initialization/use> !!!
This happens because send_linger_ping() always (re)uses the same OSD
request for watch ping requests, relying on cancel_linger_request() to
unregister it from the OSD client and rip its messages out from the
messenger. send_linger() does the same for watch/notify registration
and watch reconnect requests. Unfortunately cancel_request() doesn't
guarantee that after it returns the OSD client would be completely done
with the OSD request -- a ref could still be held and the callback (if
specified) could still be invoked too.
The original motivation for request_reinit() was inability to deal with
allocation failures in send_linger() and send_linger_ping(). Switching
to using osdc->req_mempool (currently only used by CephFS) respects that
and allows us to get rid of request_reinit().
Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
|
||
|---|---|---|
| .. | ||
| 6lowpan | ||
| 9p | ||
| 802 | ||
| 8021q | ||
| appletalk | ||
| atm | ||
| ax25 | ||
| batman-adv | ||
| bluetooth | ||
| bpf | ||
| bpfilter | ||
| bridge | ||
| caif | ||
| can | ||
| ceph | ||
| core | ||
| dcb | ||
| dccp | ||
| decnet | ||
| dns_resolver | ||
| dsa | ||
| ethernet | ||
| ethtool | ||
| hsr | ||
| ieee802154 | ||
| ife | ||
| ipv4 | ||
| ipv6 | ||
| iucv | ||
| kcm | ||
| key | ||
| l2tp | ||
| l3mdev | ||
| lapb | ||
| llc | ||
| mac80211 | ||
| mac802154 | ||
| mctp | ||
| mpls | ||
| mptcp | ||
| ncsi | ||
| netfilter | ||
| netlabel | ||
| netlink | ||
| netrom | ||
| nfc | ||
| nsh | ||
| openvswitch | ||
| packet | ||
| phonet | ||
| psample | ||
| qrtr | ||
| rds | ||
| rfkill | ||
| rose | ||
| rxrpc | ||
| sched | ||
| sctp | ||
| smc | ||
| strparser | ||
| sunrpc | ||
| switchdev | ||
| tipc | ||
| tls | ||
| unix | ||
| vmw_vsock | ||
| wireless | ||
| x25 | ||
| xdp | ||
| xfrm | ||
| compat.c | ||
| devres.c | ||
| Kconfig | ||
| Kconfig.debug | ||
| Makefile | ||
| socket.c | ||
| sysctl_net.c | ||