From: Eric Biggers Date: Sat, 11 Dec 2021 00:19:26 +0000 (-0800) Subject: signalfd: use wake_up_pollfree() X-Git-Tag: MMI-RSBS31.Q1-48-36-26~17 X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=1e02baef7eccf89146fd0530e17314f24d42a289;p=GitHub%2FMotorolaMobilityLLC%2Fkernel-slsi.git signalfd: use wake_up_pollfree() commit 9537bae0da1f8d1e2361ab6d0479e8af7824e160 upstream. wake_up_poll() uses nr_exclusive=1, so it's not guaranteed to wake up all exclusive waiters. Yet, POLLFREE *must* wake up all waiters. epoll and aio poll are fortunately not affected by this, but it's very fragile. Thus, the new function wake_up_pollfree() has been introduced. Convert signalfd to use wake_up_pollfree(). Mot-CRs-fixed: (CR) CVE-Fixed: CVE-2021-39698 Bug: 185125206 Change-Id: I203380553edf57ac23b249e18d937f2ec3c78671 Reported-by: Linus Torvalds Fixes: d80e731ecab4 ("epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree()") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20211209010455.42744-4-ebiggers@kernel.org Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman Signed-off-by: Gajjala Chakradhar Reviewed-on: https://gerrit.mot.com/2197700 SME-Granted: SME Approvals Granted SLTApproved: Slta Waiver Tested-by: Jira Key Reviewed-by: Xiangpo Zhao Submit-Approved: Jira Key (cherry picked from commit e6c52d9f3ac2c2af5678ba583dd223d97dca2afe) --- diff --git a/fs/signalfd.c b/fs/signalfd.c index 1c667af86da5..0b7c6c2c95b8 100644 --- a/fs/signalfd.c +++ b/fs/signalfd.c @@ -35,17 +35,7 @@ void signalfd_cleanup(struct sighand_struct *sighand) { - wait_queue_head_t *wqh = &sighand->signalfd_wqh; - /* - * The lockless check can race with remove_wait_queue() in progress, - * but in this case its caller should run under rcu_read_lock() and - * sighand_cachep is SLAB_TYPESAFE_BY_RCU, we can safely return. - */ - if (likely(!waitqueue_active(wqh))) - return; - - /* wait_queue_entry_t->func(POLLFREE) should do remove_wait_queue() */ - wake_up_poll(wqh, POLLHUP | POLLFREE); + wake_up_pollfree(&sighand->signalfd_wqh); } struct signalfd_ctx {