In the Linux kernel, the following vulnerability has been resolved: Bluetooth: bcsp: receive data only if registered Currently, bcsprecv() can be called even when the BCSP protocol has not been registered. This leads to a NULL pointer dereference, as shown in the following stack trace: KASAN: null-ptr-deref in range [0x0000000000000108-0x000000000000010f] RIP: 0010:bcsprecv+0x13d/0x1740 drivers/bluetooth/hcibcsp.c:590 Call Trace: <TASK> hciuartttyreceive+0x194/0x220 drivers/bluetooth/hcildisc.c:627 tiocsti+0x23c/0x2c0 drivers/tty/ttyio.c:2290 ttyioctl+0x626/0xde0 drivers/tty/ttyio.c:2706 vfsioctl fs/ioctl.c:51 [inline] _dosysioctl fs/ioctl.c:907 [inline] _sesysioctl+0xfc/0x170 fs/ioctl.c:893 dosyscallx64 arch/x86/entry/syscall64.c:63 [inline] dosyscall64+0xfa/0x3b0 arch/x86/entry/syscall64.c:94 entrySYSCALL64afterhwframe+0x77/0x7f To prevent this, ensure that the HCIUART_REGISTERED flag is set before processing received data. If the protocol is not registered, return -EUNATCH.