CVE-2022-49900 i2c: piix4: Fix adapter not be removed in piix4_remove()
A use-after-free vulnerability in the Linux kernel's i2c piix4 driver allows attackers to cause a system crash or potentially execute code via module removal.
- 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-2022-49900?
CVE-2022-49900 is a high-severity use after free vulnerability in Linux kernel, published on 1 May 2025. 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:
i2c: piix4: Fix adapter not be removed in piix4_remove()
In piix4_probe(), the piix4 adapter will be registered in:
piix4_probe() piix4_add_adapters_sb800() / piix4_add_adapter() i2c_add_adapter()
Based on the probed device type, piix4_add_adapters_sb800() or single piix4_add_adapter() will be called. For the former case, piix4_adapter_count is set as the number of adapters, while for antoher case it is not set and kept default *zero*.
When piix4 is removed, piix4_remove() removes the adapters added in piix4_probe(), basing on the piix4_adapter_count value. Because the count is zero for the single adapter case, the adapter won't be removed and makes the sources allocated for adapter leaked, such as the i2c client and device.
These sources can still be accessed by i2c or bus and cause problems. An easily reproduced case is that if a new adapter is registered, i2c will get the leaked adapter and try to call smbus_algorithm, which was already freed:
Triggered by: rmmod i2c_piix4 && modprobe max31730
BUG: unable to handle page fault for address: ffffffffc053d860 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 3752 Comm: modprobe Tainted: G Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:i2c_default_probe (drivers/i2c/i2c-core-base.c:2259) i2c_core RSP: 0018:ffff888107477710 EFLAGS: 00000246 ... <TASK> i2c_detect (drivers/i2c/i2c-core-base.c:2302) i2c_core __process_new_driver (drivers/i2c/i2c-core-base.c:1336) i2c_core bus_for_each_dev (drivers/base/bus.c:301) i2c_for_each_dev (drivers/i2c/i2c-core-base.c:1823) i2c_core i2c_register_driver (drivers/i2c/i2c-core-base.c:1861) i2c_core do_one_initcall (init/main.c:1296) do_init_module (kernel/module/main.c:2455) ... </TASK> ---[ end trace 0000000000000000 ]---
Fix this problem by correctly set piix4_adapter_count as 1 for the single adapter so it can be normally removed.
Weakness: CWE-415
Which versions are affected by CVE-2022-49900?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-49900?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2022-49900 being exploited?
There is no known exploitation of CVE-2022-49900 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-49900, GHSA-h3mh-rq8w-j65m, UBUNTU-CVE-2022-49900.