From 0f1d33872aa3be05a0e7cdd87ba68f579ef4730a Mon Sep 17 00:00:00 2001
From: Dongliang Mu <mudongliangabcd@gmail.com>
Date: Tue, 27 Sep 2022 06:23:54 +0000
Subject: [PATCH] media: em28xx: initialize refcount before kref_get
stable inclusion
from stable-v4.19.238
commit 0113fa98a49a8e46a19b0ad80f29c904c6feec23
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5RX5X
CVE: CVE-2022-3239
---------------------------
[ Upstream commit c08eadca1bdfa099e20a32f8fa4b52b2f672236d ]
The commit 47677e51e2a4("[media] em28xx: Only deallocate struct
em28xx after finishing all extensions") adds kref_get to many init
functions (e.g., em28xx_audio_init). However, kref_init is called too
late in em28xx_usb_probe, since em28xx_init_dev before will invoke
those init functions and call kref_get function. Then refcount bug
occurs in my local syzkaller instance.
Fix it by moving kref_init before em28xx_init_dev. This issue occurs
not only in dev but also dev->dev_next.
Fixes: 47677e51e2a4 ("[media] em28xx: Only deallocate struct em28xx after finishing all extensions")
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Guo Mengqi <guomengqi3@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>
---
drivers/media/usb/em28xx/em28xx-cards.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c
index 3f59a98dbf9a..00a3b5768b9a 100644
--- a/drivers/media/usb/em28xx/em28xx-cards.c
+++ b/drivers/media/usb/em28xx/em28xx-cards.c
@@ -3816,6 +3816,8 @@ static int em28xx_usb_probe(struct usb_interface *intf,
goto err_free;
}
+ kref_init(&dev->ref);
+
dev->devno = nr;
dev->model = id->driver_info;
dev->alt = -1;
@@ -3916,6 +3918,8 @@ static int em28xx_usb_probe(struct usb_interface *intf,
}
if (dev->board.has_dual_ts && em28xx_duplicate_dev(dev) == 0) {
+ kref_init(&dev->dev_next->ref);
+
dev->dev_next->ts = SECONDARY_TS;
dev->dev_next->alt = -1;
dev->dev_next->is_audio_only = has_vendor_audio &&
@@ -3970,12 +3974,8 @@ static int em28xx_usb_probe(struct usb_interface *intf,
em28xx_write_reg(dev, 0x0b, 0x82);
mdelay(100);
}
-
- kref_init(&dev->dev_next->ref);
}
- kref_init(&dev->ref);
-
request_modules(dev);
/*
--
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