CVE-2022-49940

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

tty: n_gsm: add sanity check for gsm->receive in gsm_receive_buf()

A null pointer dereference can happen when attempting to access the

"gsm->receive()" function in gsmld_receive_buf(). Currently, the code

assumes that gsm->recieve is only called after MUX activation.

Since the gsmld_receive_buf() function can be accessed without the need to

initialize the MUX, the gsm->receive() function will not be set and a

NULL pointer dereference will occur.

Fix this by avoiding the call to "gsm->receive()" in case the function is

not initialized by adding a sanity check.

Call Trace:

<TASK>

gsmld_receive_buf+0x1c2/0x2f0 drivers/tty/n_gsm.c:2861

tiocsti drivers/tty/tty_io.c:2293 [inline]

tty_ioctl+0xa75/0x15d0 drivers/tty/tty_io.c:2692

vfs_ioctl fs/ioctl.c:51 [inline]

__do_sys_ioctl fs/ioctl.c:870 [inline]

__se_sys_ioctl fs/ioctl.c:856 [inline]

__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856

do_syscall_x64 arch/x86/entry/com

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References