svn commit: r340898 - head/sys/kern
Mark Johnston
markj at FreeBSD.org
Sat Nov 24 16:58:35 UTC 2018
Author: markj
Date: Sat Nov 24 16:58:34 2018
New Revision: 340898
URL: https://svnweb.freebsd.org/changeset/base/340898
Log:
Ensure that knotes do not get registered when KQ_CLOSING is set.
KQ_CLOSING is set before draining the knotes associated with a kqueue,
so we must ensure that new knotes are not added after that point. In
particular, some kernel facilities may register for events on behalf
of a userspace process and race with a close of the kqueue.
PR: 228858
Reviewed by: kib
Tested by: pho
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D18316
Modified:
head/sys/kern/kern_event.c
Modified: head/sys/kern/kern_event.c
==============================================================================
--- head/sys/kern/kern_event.c Sat Nov 24 16:41:29 2018 (r340897)
+++ head/sys/kern/kern_event.c Sat Nov 24 16:58:34 2018 (r340898)
@@ -1460,8 +1460,11 @@ findkn:
break;
}
} else {
- if ((kev->flags & EV_ADD) == EV_ADD)
- kqueue_expand(kq, fops, kev->ident, waitok);
+ if ((kev->flags & EV_ADD) == EV_ADD) {
+ error = kqueue_expand(kq, fops, kev->ident, waitok);
+ if (error != 0)
+ goto done;
+ }
KQ_LOCK(kq);
@@ -1693,12 +1696,12 @@ kqueue_expand(struct kqueue *kq, struct filterops *fop
{
struct klist *list, *tmp_knhash, *to_free;
u_long tmp_knhashmask;
- int size;
- int fd;
+ int error, fd, size;
int mflag = waitok ? M_WAITOK : M_NOWAIT;
KQ_NOTOWNED(kq);
+ error = 0;
to_free = NULL;
if (fops->f_isfd) {
fd = ident;
@@ -1710,9 +1713,11 @@ kqueue_expand(struct kqueue *kq, struct filterops *fop
if (list == NULL)
return ENOMEM;
KQ_LOCK(kq);
- if (kq->kq_knlistsize > fd) {
+ if ((kq->kq_state & KQ_CLOSING) != 0) {
to_free = list;
- list = NULL;
+ error = EBADF;
+ } else if (kq->kq_knlistsize > fd) {
+ to_free = list;
} else {
if (kq->kq_knlist != NULL) {
bcopy(kq->kq_knlist, list,
@@ -1734,9 +1739,12 @@ kqueue_expand(struct kqueue *kq, struct filterops *fop
&tmp_knhashmask,
waitok ? HASH_WAITOK : HASH_NOWAIT);
if (tmp_knhash == NULL)
- return ENOMEM;
+ return (ENOMEM);
KQ_LOCK(kq);
- if (kq->kq_knhashmask == 0) {
+ if ((kq->kq_state & KQ_CLOSING) != 0) {
+ to_free = tmp_knhash;
+ error = EBADF;
+ } else if (kq->kq_knhashmask == 0) {
kq->kq_knhash = tmp_knhash;
kq->kq_knhashmask = tmp_knhashmask;
} else {
@@ -1748,7 +1756,7 @@ kqueue_expand(struct kqueue *kq, struct filterops *fop
free(to_free, M_KQUEUE);
KQ_NOTOWNED(kq);
- return 0;
+ return (error);
}
static void
@@ -2597,6 +2605,8 @@ knote_attach(struct knote *kn, struct kqueue *kq)
KASSERT(kn_in_flux(kn), ("knote %p not marked influx", kn));
KQ_OWNED(kq);
+ if ((kq->kq_state & KQ_CLOSING) != 0)
+ return (EBADF);
if (kn->kn_fop->f_isfd) {
if (kn->kn_id >= kq->kq_knlistsize)
return (ENOMEM);
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