high CVSS 7.8

CVE-2024-38667·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: riscv: prevent pt_regs corruption for secondary idle threads Top of the kernel thread stack should be reserved for pt_regs. However this is not the case for the idle threads of the secondary boot harts. Their stacks overlap with their pt_regs, so both may get corrupted. Similar issue has been fixed for the primary hart, see c7cdd96eca28 ("riscv: prevent stack corruption by reserving task_pt_regs(p) early"). However that fix was not propagated to the secondary harts. The problem has been noticed in some CPU hotplug tests with V enabled. The function smp_callin stored several registers on stack, corrupting top of pt_regs structure including status field. As a result, kernel attempted to save or restore inexistent V context.

Severity
high
Software
Kernel
Fixed in
6.9.4
Published
2024-06-24

Affected versions

From: 6.7

Until: 6.9.4

Fixed in: 6.9.4

How to fix this CVE

Update your Linux kernel to version 6.9.4 or later to resolve a critical pt_regs corruption issue affecting secondary CPU cores on RISC-V systems. This vulnerability can lead to kernel memory corruption and system instability, particularly during CPU hotplug operations. Immediate kernel patching and system reboot are required to apply the fix.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your current kernel version with `uname -r` and compare against the affected range (6.7 to 6.9.3)
  2. Step 2: Verify RISC-V architecture support and secondary CPU presence with `cat /proc/cpuinfo | grep -i riscv` and `nproc --all`
  3. Step 3: Search kernel logs for pt_regs corruption or V extension context errors using `journalctl -k | grep -i 'pt_regs\|vector\|V extension'`
  4. Step 4: Confirm the patch is applied by checking if kernel version is 6.9.4 or later with `uname -r` and verifying stack alignment with `cat /proc/sys/kernel/kptr_restrict`

FAQ

What is CVE-2024-38667?

CVE-2024-38667 is a memory corruption vulnerability in the Linux kernel's RISC-V architecture where the kernel stack of secondary CPU cores overlaps with the pt_regs (processor state) structure, allowing register data to be corrupted when secondary CPUs are initialized or during CPU hotplug operations.

Is CVE-2024-38667 being actively exploited?

No. This vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog and no public exploits are currently available. However, its high CVSS score (7.8) indicates serious potential impact and should still be prioritized for patching.

What versions of Kernel are affected by CVE-2024-38667?

Linux kernel versions 6.7 through 6.9.3 are affected. The vulnerability was patched in kernel 6.9.4 and subsequent releases. RISC-V systems are the primary target, particularly those with multiple CPU cores or V (Vector) extension support.

How do I check if my server is vulnerable to CVE-2024-38667?

Run `uname -r` to check your kernel version. If it reports a version between 6.7 and 6.9.3, you are vulnerable. You can additionally check for RISC-V architecture with `uname -m` and CPU count with `nproc --all`.

Does Defensia detect CVE-2024-38667?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2024-38667 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-2024-36031CVSS 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)
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-2021-47548CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ethernet: hisilicon: hns: hns_dsaf_misc: fix a possible array overflow in hns_dsaf_ge_srst_by_port() The if statement: if (port >= DSAF_GE_NUM) return; limits the value of port less than DSAF_GE_NUM (i.e., 8). However, if the value of port is 6 or 7, an array overflow could occur: port_rst_off = dsaf_dev->mac_cb[port]->port_rst_off; because the length of dsaf_dev->mac_cb is DSAF_MAX_PORT_NUM (i.e., 6). To fix this possible array overflow, we first check port and if it is greater than or equal to DSAF_MAX_PORT_NUM, the function returns.

References

Track CVEs across your fleet automatically

Defensia scans your Linux servers and tells you exactly which ones are running vulnerable versions — including CVE-2024-38667. Free for 1 server.

Get started free