media: netup_unidvb: fix use-after-free at del_timer()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: media: netup_unidvb: fix use-after-free at del_timer() When Universal DVB card is detaching, netup_unidvb_dma_fini() uses del_timer() to stop dma->timeout timer. But when timer handler netup_unidvb_dma_timeout() is running, del_timer() could not stop it. As a result, the use-after-free bug could happen. The process is shown below: (cleanup routine) | (timer routine) | mod_timer(&dev->tx_sim_timer, ..) netup_unidvb_finidev() | (wait a time) netup_unidvb_dma_fini() | netup_unidvb_dma_timeout() del_timer(&dma->timeout); | | ndev->pci_dev->dev //USE Fix by changing del_timer() to del_timer_sync().

References

• https://git.kernel.org/stable/c/dd5c77814f290b353917df329f36de1472d47154
• https://git.kernel.org/stable/c/90229e9ee957d4514425e4a4d82c50ab5d57ac4d
• https://git.kernel.org/stable/c/1550bcf2983ae1220cc8ab899a39a423fa7cb523
• https://git.kernel.org/stable/c/f9982db735a8495eee14267cf193c806b957e942
• https://git.kernel.org/stable/c/051af3f0b7d1cd8ab7f3e2523ad8ae1af44caba3
• https://git.kernel.org/stable/c/07821524f67bf920342bc84ae8b3dea2a315a89e
• https://git.kernel.org/stable/c/c8f9c05e1ebcc9c7bc211cc8b74d8fb86a8756fc
• https://git.kernel.org/stable/c/0f5bb36bf9b39a2a96e730bf4455095b50713f63