high CVSS 7.8

CVE-2024-38630·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: watchdog: cpu5wdt.c: Fix use-after-free bug caused by cpu5wdt_trigger When the cpu5wdt module is removing, the origin code uses del_timer() to de-activate the timer. If the timer handler is running, del_timer() could not stop it and will return directly. If the port region is released by release_region() and then the timer handler cpu5wdt_trigger() calls outb() to write into the region that is released, the use-after-free bug will happen. Change del_timer() to timer_shutdown_sync() in order that the timer handler could be finished before the port region is released.

Severity
high
Software
Kernel
Fixed in
6.9.4
Published
2024-06-21

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 this use-after-free vulnerability in the cpu5wdt watchdog driver. The fix replaces an unsafe timer deactivation method with a synchronous shutdown that ensures the timer handler completes before hardware port resources are released. Systems running kernels 6.7 through 6.9.3 should prioritize this update to prevent potential kernel memory corruption.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your kernel version with 'uname -r' and compare against 6.9.4 — versions 6.7.x through 6.9.3 are vulnerable
  2. Step 2: Verify if cpu5wdt module is loaded by running 'lsmod | grep cpu5wdt' — if present, your system uses this watchdog driver
  3. Step 3: Search kernel logs for timer-related crashes or memory access violations using 'sudo dmesg | grep -i "use-after-free\|cpu5wdt\|outb"'
  4. Step 4: After patching, confirm the new kernel is running with 'uname -r' and verify it shows 6.9.4 or higher

FAQ

What is CVE-2024-38630?

This is a use-after-free vulnerability in the Linux kernel's cpu5wdt watchdog driver module. When the module is unloaded, a race condition allows the timer handler to write to freed I/O port memory, potentially causing kernel corruption or crashes.

Is CVE-2024-38630 being actively exploited?

No, this vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities catalog and no public exploits are available. However, it remains a high-severity issue due to its potential impact on system stability.

What versions of Kernel are affected by CVE-2024-38630?

Linux kernel versions 6.7.0 through 6.9.3 are vulnerable. The fix was released in kernel 6.9.4.

How do I check if my server is vulnerable to CVE-2024-38630?

Run 'uname -r' to get your kernel version. If it shows 6.7.x, 6.8.x, or 6.9.0-6.9.3, you are vulnerable. Additionally, check if 'lsmod | grep cpu5wdt' shows the watchdog driver is loaded.

Does Defensia detect CVE-2024-38630?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2024-38630 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

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