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Subject[PATCH (resend)] Input: uinput - Set name/phys to NULL before kfree().
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syzbot is hitting use-after-free bug in uinput module [1]. This is because
uinput_destroy_device() sometimes kfree()s dev->name and dev->phys at
uinput_destroy_device() before dev_uevent() is triggered by dropping the
refcount to 0. Since the timing of triggering last input_put_device() is
uncontrollable, this patch prepares for such race by setting dev->name and
dev->phys to NULL before doing operations which might drop the refcount
to 0.

[1] https://syzkaller.appspot.com/bug?id=8b17c134fe938bbddd75a45afaa9e68af43a362d

Reported-by: syzbot <syzbot+f648cfb7e0b52bf7ae32@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
drivers/input/misc/uinput.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index 8ec483e8688b..131591b5babd 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -300,7 +300,9 @@ static void uinput_destroy_device(struct uinput_device *udev)

if (dev) {
name = dev->name;
+ dev->name = NULL;
phys = dev->phys;
+ dev->phys = NULL;
if (old_state == UIST_CREATED) {
uinput_flush_requests(udev);
input_unregister_device(dev);
--
2.17.1
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