From: Dongliang Mu mudongliangabcd@gmail.com

stable inclusion from stable-v4.19.238 commit 0113fa98a49a8e46a19b0ad80f29c904c6feec23 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5RX5X CVE: CVE-2022-3239

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[ 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);

/*