In the Linux kernel, the following vulnerability has been resolved: serial: max3100: Update uart_driver_registered on driver removal The removal of the last MAX3100 device triggers the removal of the driver. However, code doesn't update the respective global variable and after insmod — rmmod — insmod cycle the kernel oopses: max3100 spi-PRP0001:01: max3100_probe: adding port 0 BUG: kernel NULL pointer dereference, address: 0000000000000408 ... RIP: 0010:serial_core_register_port+0xa0/0x840 ... max3100_probe+0x1b6/0x280 [max3100] spi_probe+0x8d/0xb0 Update the actual state so next time UART driver will be registered again. Hugo also noticed, that the error path in the probe also affected by having the variable set, and not cleared. Instead of clearing it move the assignment after the successfull uart_register_driver() call.
https://git.kernel.org/stable/c/fa84ca78b048dfb00df0ef446f5c35e0a98ca6a0
https://git.kernel.org/stable/c/e8e2a4339decad7e59425b594a98613402652d72
https://git.kernel.org/stable/c/e8a10089eddba40d4b2080c9d3fc2d2b2488f762
https://git.kernel.org/stable/c/b6eb7aff23e05f362e8c9b560f6ac5e727b70e00
https://git.kernel.org/stable/c/9db4222ed8cd3e50b81c8b910ae74c26427a4003
https://git.kernel.org/stable/c/712a1fcb38dc7cac6da63ee79a88708fbf9c45ec
https://git.kernel.org/stable/c/361a92c9038e8c8c3996f8eeaa14522a8ad90752
https://git.kernel.org/stable/c/21a61a7fbcfdd3493cede43ebc7c4dfae2147a8b