CVE-2022-48649 mm/slab_common: fix possible double free of kmem_cache
A race condition in the Linux kernel memory allocator can cause a double free, potentially allowing local attackers to execute arbitrary code or escalate privileges.
- 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-2022-48649?
CVE-2022-48649 is a high-severity use after free vulnerability in Linux kernel, published on 28 Apr 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:
mm/slab_common: fix possible double free of kmem_cache
When doing slub_debug test, kfence's 'test_memcache_typesafe_by_rcu' kunit test case cause a use-after-free error:
BUG: KASAN: use-after-free in kobject_del+0x14/0x30 Read of size 8 at addr ffff888007679090 by task kunit_try_catch/261
CPU: 1 PID: 261 Comm: kunit_try_catch Tainted: G B N 6.0.0-rc5-next-20220916 #17 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x34/0x48 print_address_description.constprop.0+0x87/0x2a5 print_report+0x103/0x1ed kasan_report+0xb7/0x140 kobject_del+0x14/0x30 kmem_cache_destroy+0x130/0x170 test_exit+0x1a/0x30 kunit_try_run_case+0xad/0xc0 kunit_generic_run_threadfn_adapter+0x26/0x50 kthread+0x17b/0x1b0 </TASK>
The cause is inside kmem_cache_destroy():
kmem_cache_destroy acquire lock/mutex shutdown_cache schedule_work(kmem_cache_release) (if RCU flag set) release lock/mutex kmem_cache_release (if RCU flag not set)
In some certain timing, the scheduled work could be run before the next RCU flag checking, which can then get a wrong value and lead to double kmem_cache_release().
Fix it by caching the RCU flag inside protected area, just like 'refcnt'
Which versions are affected by CVE-2022-48649?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-48649?
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-2022-48649 being exploited?
There is no known exploitation of CVE-2022-48649 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-48649, GHSA-mcvj-6jjv-7hw9, UBUNTU-CVE-2022-48649.