Vulnerability CVE-2024-38633
Published: 2024-06-21

Description:
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.

 References:
https://git.kernel.org/stable/c/21a61a7fbcfdd3493cede43ebc7c4dfae2147a8b
https://git.kernel.org/stable/c/9db4222ed8cd3e50b81c8b910ae74c26427a4003
https://git.kernel.org/stable/c/e8e2a4339decad7e59425b594a98613402652d72
https://git.kernel.org/stable/c/361a92c9038e8c8c3996f8eeaa14522a8ad90752
https://git.kernel.org/stable/c/b6eb7aff23e05f362e8c9b560f6ac5e727b70e00
https://git.kernel.org/stable/c/e8a10089eddba40d4b2080c9d3fc2d2b2488f762
https://git.kernel.org/stable/c/fa84ca78b048dfb00df0ef446f5c35e0a98ca6a0
https://git.kernel.org/stable/c/712a1fcb38dc7cac6da63ee79a88708fbf9c45ec
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