CVE-2022-49940

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> tty: n_gsm: add sanity check for gsm-&gt;receive in gsm_receive_buf()<br /> <br /> A null pointer dereference can happen when attempting to access the<br /> "gsm-&gt;receive()" function in gsmld_receive_buf(). Currently, the code<br /> assumes that gsm-&gt;recieve is only called after MUX activation.<br /> Since the gsmld_receive_buf() function can be accessed without the need to<br /> initialize the MUX, the gsm-&gt;receive() function will not be set and a<br /> NULL pointer dereference will occur.<br /> <br /> Fix this by avoiding the call to "gsm-&gt;receive()" in case the function is<br /> not initialized by adding a sanity check.<br /> <br /> Call Trace:<br /> <br /> gsmld_receive_buf+0x1c2/0x2f0 drivers/tty/n_gsm.c:2861<br /> tiocsti drivers/tty/tty_io.c:2293 [inline]<br /> tty_ioctl+0xa75/0x15d0 drivers/tty/tty_io.c:2692<br /> vfs_ioctl fs/ioctl.c:51 [inline]<br /> __do_sys_ioctl fs/ioctl.c:870 [inline]<br /> __se_sys_ioctl fs/ioctl.c:856 [inline]<br /> __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856<br /> do_syscall_x64 arch/x86/entry/common.c:50 [inline]<br /> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80<br /> entry_SYSCALL_64_after_hwframe+0x63/0xcd