CVE-2022-48870 tty: fix possible null-ptr-defer in spk_ttyio_release
A null pointer dereference in the Linux kernel's speakup module allows local attackers to cause a system crash by removing the module after failed initialization.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-48870?
CVE-2022-48870 is a medium-severity vulnerability in Linux kernel, published on 21 Aug 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
tty: fix possible null-ptr-defer in spk_ttyio_release
Run the following tests on the qemu platform:
syzkaller:~# modprobe speakup_audptr input: Speakup as /devices/virtual/input/input4 initialized device: /dev/synth, node (MAJOR 10, MINOR 125) speakup 3.1.6: initialized synth name on entry is: (null) synth probe
spk_ttyio_initialise_ldisc failed because tty_kopen_exclusive returned failed (errno -16), then remove the module, we will get a null-ptr-defer problem, as follow:
syzkaller:~# modprobe -r speakup_audptr releasing synth audptr BUG: kernel NULL pointer dereference, address: 0000000000000080 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] PREEMPT SMP PTI CPU: 2 PID: 204 Comm: modprobe Not tainted 6.1.0-rc6-dirty #1 RIP: 0010:mutex_lock+0x14/0x30 Call Trace: <TASK> spk_ttyio_release+0x19/0x70 [speakup] synth_release.part.6+0xac/0xc0 [speakup] synth_remove+0x56/0x60 [speakup] __x64_sys_delete_module+0x156/0x250 ? fpregs_assert_state_consistent+0x1d/0x50 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd </TASK> Modules linked in: speakup_audptr(-) speakup Dumping ftrace buffer:
in_synth->dev was not initialized during modprobe, so we add check for in_synth->dev to fix this bug.
Weakness: CWE-476
Which versions are affected by CVE-2022-48870?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-48870?
Apply the vendor's patch.
Is CVE-2022-48870 being exploited?
There is no known exploitation of CVE-2022-48870 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-48870, GHSA-5hgq-f2qx-82g9, UBUNTU-CVE-2022-48870.