high CVSS 7.8

CVE-2024-26884·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix hashtab overflow check on 32-bit arches The hashtab code relies on roundup_pow_of_two() to compute the number of hash buckets, and contains an overflow check by checking if the resulting value is 0. However, on 32-bit arches, the roundup code itself can overflow by doing a 32-bit left-shift of an unsigned long value, which is undefined behaviour, so it is not guaranteed to truncate neatly. This was triggered by syzbot on the DEVMAP_HASH type, which contains the same check, copied from the hashtab code. So apply the same fix to hashtab, by moving the overflow check to before the roundup.

Severity
high
Software
Kernel
Fixed in
6.8.2
Published
2024-04-17

Affected versions

From: 6.8

Until: 6.8.2

Fixed in: 6.8.2

How to fix this CVE

Update your Linux kernel to version 6.8.2 or later to resolve a critical hashtable overflow vulnerability affecting 32-bit architectures. This fix relocates the overflow validation to occur before the roundup operation, preventing undefined behavior that could lead to memory corruption or privilege escalation. Perform a kernel update followed by a system reboot to ensure the patched version is active.

sudo dnf update kernel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'uname -r' to display your currently running kernel version and verify it is 6.8.2 or higher
  2. Check if BPF programs (eBPF) are loaded on your system using 'bpftool prog list' if the bpf-tools package is installed
  3. Search kernel logs for hashtable allocation failures: 'grep -i hashtab /var/log/kern.log' or 'journalctl -k | grep -i hashtab'
  4. Confirm patch application by verifying kernel build date: 'cat /proc/version' should show a build date after the CVE-2024-26884 fix release

FAQ

What is CVE-2024-26884?

This vulnerability is an integer overflow in the Linux kernel's BPF hashtable implementation on 32-bit architectures. The overflow check was performed after a potentially unsafe shift operation, allowing undefined behavior that could corrupt kernel memory or enable privilege escalation.

Is CVE-2024-26884 being actively exploited?

No, there are no known public exploits or active exploitation campaigns documented for this vulnerability. However, it affects core kernel functionality and should be patched promptly.

What versions of Kernel are affected by CVE-2024-26884?

Linux kernel versions 6.8 through 6.8.1 on 32-bit architectures are vulnerable. The issue was resolved in kernel 6.8.2 and later.

How do I check if my server is vulnerable to CVE-2024-26884?

Run 'uname -r' to check your kernel version. If the output shows version 6.8.0, 6.8.1, or 6.8.x (where x < 2) on a 32-bit system, your server is vulnerable. Run 'uname -m' to verify your architecture (i386 or i686 indicates 32-bit).

Does Defensia detect CVE-2024-26884?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2024-26884 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-2024-38541CVSS 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-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.
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-2022-48716CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ASoC: codecs: wcd938x: fix incorrect used of portid Mixer controls have the channel id in mixer->reg, which is not same as port id. port id should be derived from chan_info array. So fix this. Without this, its possible that we could corrupt struct wcd938x_sdw_priv by accessing port_map array out of range with channel id instead of port id.

References

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