From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>
Cc: linux-kernel@vger.kernel.org,
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Kay Sievers <kay@vrfy.org>,
syzbot <syzbot+f648cfb7e0b52bf7ae32@syzkaller.appspotmail.com>
Subject: [PATCH] kobject: Don't trigger kobject_uevent(KOBJ_REMOVE) twice.
Date: Wed, 20 Feb 2019 22:38:34 +0900 [thread overview]
Message-ID: <1550669914-10704-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp> (raw)
syzbot is hitting use-after-free bug in uinput module [1]. This is because
kobject_uevent(KOBJ_REMOVE) is called again due to commit 0f4dafc0563c6c49
("Kobject: auto-cleanup on final unref") after memory allocation fault
injection made kobject_uevent(KOBJ_REMOVE) from device_del() from
input_unregister_device() fail, while uinput_destroy_device() is expecting
that kobject_uevent(KOBJ_REMOVE) is not called after device_del() from
input_unregister_device() completed. Fix this problem by marking "remove"
event done regardless of result.
[1] https://syzkaller.appspot.com/bug?id=8b17c134fe938bbddd75a45afaa9e68af43a362d
Reported-by: syzbot <syzbot+f648cfb7e0b52bf7ae32@syzkaller.appspotmail.com>
Analyzed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Kay Sievers <kay@vrfy.org>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
lib/kobject_uevent.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index f058026..7ec4165 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -466,6 +466,13 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
int i = 0;
int retval = 0;
+ /*
+ * Mark "remove" event done regardless of result, for some subsystems
+ * do not want to re-trigger "remove" event via automatic cleanup.
+ */
+ if (action == KOBJ_REMOVE && kobj->state_add_uevent_sent)
+ kobj->state_remove_uevent_sent = 1;
+
pr_debug("kobject: '%s' (%p): %s\n",
kobject_name(kobj), kobj, __func__);
@@ -567,10 +574,6 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
kobj->state_add_uevent_sent = 1;
break;
- case KOBJ_REMOVE:
- kobj->state_remove_uevent_sent = 1;
- break;
-
case KOBJ_UNBIND:
zap_modalias_env(env);
break;
--
1.8.3.1
next reply other threads:[~2019-02-20 13:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-20 13:38 Tetsuo Handa [this message]
2019-02-20 15:07 ` [PATCH] kobject: Don't trigger kobject_uevent(KOBJ_REMOVE) twice Greg Kroah-Hartman
2019-02-20 19:52 ` Dmitry Torokhov
2019-02-21 10:40 ` Tetsuo Handa
2019-02-21 11:09 ` Greg Kroah-Hartman
2019-02-21 12:31 ` Tetsuo Handa
2019-02-27 10:21 ` Tetsuo Handa
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