| Message ID | 1499631595-12625-1-git-send-email-xiyou.wangcong@gmail.com |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
On Sun, Jul 9, 2017 at 1:19 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote: > > Setting 'sock' to NULL here should be sufficient to fix it. Thanks. Applied and marked for stable. Linus
diff --git a/ipc/mqueue.c b/ipc/mqueue.c index c9ff943..eb1391b 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -1270,8 +1270,10 @@ static int do_mq_notify(mqd_t mqdes, const struct sigevent *notification) timeo = MAX_SCHEDULE_TIMEOUT; ret = netlink_attachskb(sock, nc, &timeo, NULL); - if (ret == 1) + if (ret == 1) { + sock = NULL; goto retry; + } if (ret) { sock = NULL; nc = NULL;
The retry logic for netlink_attachskb() inside sys_mq_notify() is nasty and vulnerable: 1) The sock refcnt is already released when retry is needed 2) The fd is controllable by user-space because we already release the file refcnt so we when retry but the fd has been just closed by user-space during this small window, we end up calling netlink_detachskb() on the error path which releases the sock again, later when the user-space closes this socket a use-after-free could be triggered. Setting 'sock' to NULL here should be sufficient to fix it. Reported-by: GeneBlue <geneblue.mail@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> --- ipc/mqueue.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)