CVE-2024-38633

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 doesnt 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.

Weakness

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.

Affected Software

Potential Mitigations

References

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