high CVSS 7.8

CVE-2024-36906·Kernel vulnerability

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")

Severity
high
Software
Kernel
Fixed in
6.8.10
Published
2024-05-30

Affected versions

From: 6.7

Until: 6.8.10

Fixed in: 6.8.10

How to fix this CVE

Update your Linux kernel to version 6.8.10 or later to patch CVE-2024-36906, which causes stack-out-of-bounds errors during CPU idle transitions on ARM systems. This fix clears stale KASAN poison metadata left by instrumented functions during cpuidle operations, preventing false memory safety violations. Apply the update immediately if you run ARM-based systems with KASAN enabled.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check current kernel version with: uname -r
  2. Verify if kernel was compiled with KASAN support: grep -i kasan /boot/config-$(uname -r)
  3. Search system logs for KASAN stack-out-of-bounds errors during idle transitions: journalctl -b | grep -i 'kasan.*stack-out-of-bounds'
  4. Confirm the fix by checking if updated kernel version is 6.8.10 or later: uname -r | grep -E '(6\.9|6\.8\.1[0-9]|7\.)'
  5. Verify KASAN stack poisoning is properly cleared after CPU transitions: dmesg | grep -i 'kasan' | tail -20

FAQ

What is CVE-2024-36906?

CVE-2024-36906 is a kernel memory safety vulnerability affecting ARM systems where KASAN-instrumented functions leave stale poison markers on the stack during CPU idle transitions, causing spurious out-of-bounds errors when the CPU resumes from low-power states.

Is CVE-2024-36906 being actively exploited?

No, CVE-2024-36906 is not listed in CISA's Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available. This is primarily a reliability and debugging issue rather than a security exploit vector.

What versions of Kernel are affected by CVE-2024-36906?

Linux kernel versions 6.7 through 6.8.9 are affected. The vulnerability is fixed in kernel 6.8.10 and later releases.

How do I check if my server is vulnerable to CVE-2024-36906?

Run: uname -r to check your kernel version. If it reports 6.7.x through 6.8.9, and your kernel was compiled with CONFIG_KASAN_STACK enabled (verify with: grep CONFIG_KASAN_STACK /boot/config-$(uname -r)), your system is vulnerable.

Does Defensia detect CVE-2024-36906?

Yes — Defensia's CVE advisory scanner compares installed kernel package versions against the NVD database. If the Linux kernel is installed on a monitored server and running a vulnerable version, CVE-2024-36906 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2024-42256CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: cifs: Fix server re-repick on subrequest retry When a subrequest is marked for needing retry, netfs will call cifs_prepare_write() which will make cifs repick the server for the op before renegotiating credits; it then calls cifs_issue_write() which invokes smb2_async_writev() - which re-repicks the server. If a different server is then selected, this causes the increment of server->in_flight to happen against one record and the decrement to happen against another, leading to misaccounting. Fix this by just removing the repick code in smb2_async_writev(). As this is only called from netfslib-driven code, cifs_prepare_write() should always have been called first, and so server should never be NULL and the preparatory step is repeated in the event that we do a retry. The problem manifests as a warning looking something like: WARNING: CPU: 4 PID: 72896 at fs/smb/client/smb2ops.c:97 smb2_add_credits+0x3f0/0x9e0 [cifs] ... RIP: 0010:smb2_add_credits+0x3f0/0x9e0 [cifs] ... smb2_writev_callback+0x334/0x560 [cifs] cifs_demultiplex_thread+0x77a/0x11b0 [cifs] kthread+0x187/0x1d0 ret_from_fork+0x34/0x60 ret_from_fork_asm+0x1a/0x30 Which may be triggered by a number of different xfstests running against an Azure server in multichannel mode. generic/249 seems the most repeatable, but generic/215, generic/249 and generic/308 may also show it.
CVE-2024-38612CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ipv6: sr: fix invalid unregister error path The error path of seg6_init() is wrong in case CONFIG_IPV6_SEG6_LWTUNNEL is not defined. In that case if seg6_hmac_init() fails, the genl_unregister_family() isn't called. This issue exist since commit 46738b1317e1 ("ipv6: sr: add option to control lwtunnel support"), and commit 5559cea2d5aa ("ipv6: sr: fix possible use-after-free and null-ptr-deref") replaced unregister_pernet_subsys() with genl_unregister_family() in this error path.
CVE-2024-38541CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: of: module: add buffer overflow check in of_modalias() In of_modalias(), if the buffer happens to be too small even for the 1st snprintf() call, the len parameter will become negative and str parameter (if not NULL initially) will point beyond the buffer's end. Add the buffer overflow check after the 1st snprintf() call and fix such check after the strlen() call (accounting for the terminating NUL char).
CVE-2024-36031CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: keys: Fix overwrite of key expiration on instantiation The expiry time of a key is unconditionally overwritten during instantiation, defaulting to turn it permanent. This causes a problem for DNS resolution as the expiration set by user-space is overwritten to TIME64_MAX, disabling further DNS updates. Fix this by restoring the condition that key_set_expiry is only called when the pre-parser sets a specific expiry.
CVE-2024-38623CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: Use variable length array instead of fixed size Should fix smatch warning: ntfs_set_label() error: __builtin_memcpy() 'uni->name' too small (20 vs 256)

References

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