CVE-2024-36906 ARM: 9381/1: kasan: clear stale stack poison
A stack-out-of-bounds write in the Linux kernel ARM KASAN implementation can cause a system crash, requiring a patch to clear stale stack poison.
- 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-2024-36906?
CVE-2024-36906 is a high-severity memory corruption vulnerability in Linux kernel, published on 30 May 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:
ARM: 9381/1: kasan: clear stale stack poison
We found below OOB crash:
[ 33.452494] ================================================================== [ 33.453513] BUG: KASAN: stack-out-of-bounds in refresh_cpu_vm_stats.constprop.0+0xcc/0x2ec [ 33.454660] Write of size 164 at addr c1d03d30 by task swapper/0/0 [ 33.455515] [ 33.455767] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G O 6.1.25-mainline #1 [ 33.456880] Hardware name: Generic DT based system [ 33.457555] unwind_backtrace from show_stack+0x18/0x1c [ 33.458326] show_stack from dump_stack_lvl+0x40/0x4c [ 33.459072] dump_stack_lvl from print_report+0x158/0x4a4 [ 33.459863] print_report from kasan_report+0x9c/0x148 [ 33.460616] kasan_report from kasan_check_range+0x94/0x1a0 [ 33.461424] kasan_check_range from memset+0x20/0x3c [ 33.462157] memset from refresh_cpu_vm_stats.constprop.0+0xcc/0x2ec [ 33.463064] refresh_cpu_vm_stats.constprop.0 from tick_nohz_idle_stop_tick+0x180/0x53c [ 33.464181] tick_nohz_idle_stop_tick from do_idle+0x264/0x354 [ 33.465029] do_idle from cpu_startup_entry+0x20/0x24 [ 33.465769] cpu_startup_entry from rest_init+0xf0/0xf4 [ 33.466528] rest_init from arch_post_acpi_subsys_init+0x0/0x18 [ 33.467397] [ 33.467644] The buggy address belongs to stack of task swapper/0/0 [ 33.468493] and is located at offset 112 in frame: [ 33.469172] refresh_cpu_vm_stats.constprop.0+0x0/0x2ec [ 33.469917] [ 33.470165] This frame has 2 objects: [ 33.470696] [32, 76) 'global_zone_diff' [ 33.470729] [112, 276) 'global_node_diff' [ 33.471294] [ 33.472095] The buggy address belongs to the physical page: [ 33.472862] page:3cd72da8 refcount:1 mapcount:0 mapping:00000000 index:0x0 pfn:0x41d03 [ 33.473944] flags: 0x1000(reserved|zone=0) [ 33.474565] raw: 00001000 ed741470 ed741470 00000000 00000000 00000000 ffffffff 00000001 [ 33.475656] raw: 00000000 [ 33.476050] page dumped because: kasan: bad access detected [ 33.476816] [ 33.477061] Memory state around the buggy address: [ 33.477732] c1d03c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 33.478630] c1d03c80: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00 [ 33.479526] >c1d03d00: 00 04 f2 f2 f2 f2 00 00 00 00 00 00 f1 f1 f1 f1 [ 33.480415] ^ [ 33.481195] c1d03d80: 00 00 00 00 00 00 00 00 00 00 04 f3 f3 f3 f3 f3 [ 33.482088] c1d03e00: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 [ 33.482978] ==================================================================
We find the root cause of this OOB is that arm does not clear stale stack poison in the case of cpuidle.
This patch refer to arch/arm64/kernel/sleep.S to resolve this issue.
From cited commit [1] that explain the problem
Functions which the compiler has instrumented for KASAN place poison on the stack shadow upon entry and remove this poison prior to returning.
In the case of cpuidle, CPUs exit the kernel a number of levels deep in C code. Any instrumented functions on this critical path will leave portions of the stack shadow poisoned.
If CPUs lose context and return to the kernel via a cold path, we restore a prior context saved in __cpu_suspend_enter are forgotten, and we never remove the poison they placed in the stack shadow area by functions calls between this and the actual exit of the kernel.
Thus, (depending on stackframe layout) subsequent calls to instrumented functions may hit this stale poison, resulting in (spurious) KASAN splats to the console.
To avoid this, clear any stale poison from the idle thread for a CPU prior to bringing a CPU online.
From cited commit [2]
Extend to check for CONFIG_KASAN_STACK
[1] commit 0d97e6d8024c ("arm64: kasan: clear stale stack poison") [2] commit d56a9ef84bd0 ("kasan, arm64: unpoison stack only with CONFIG_KASAN_STACK")
Weakness: CWE-787
Which versions are affected by CVE-2024-36906?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-36906?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2024-36906 being exploited?
There is no known exploitation of CVE-2024-36906 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-36906, DEBIAN-CVE-2024-36906, UBUNTU-CVE-2024-36906.