high CVSS 7.8

CVE-2024-42072·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix may_goto with negative offset. Zac's syzbot crafted a bpf prog that exposed two bugs in may_goto. The 1st bug is the way may_goto is patched. When offset is negative it should be patched differently. The 2nd bug is in the verifier: when current state may_goto_depth is equal to visited state may_goto_depth it means there is an actual infinite loop. It's not correct to prune exploration of the program at this point. Note, that this check doesn't limit the program to only one may_goto insn, since 2nd and any further may_goto will increment may_goto_depth only in the queued state pushed for future exploration. The current state will have may_goto_depth == 0 regardless of number of may_goto insns and the verifier has to explore the program until bpf_exit.

Severity
high
Software
Kernel
Fixed in
6.9.8
Published
2024-07-29

Affected versions

From: 6.9

Until: 6.9.8

Fixed in: 6.9.8

How to fix this CVE

Update your Linux kernel to version 6.9.8 or later to resolve two critical eBPF verifier bugs that could lead to kernel privilege escalation. The vulnerabilities affect how the may_goto instruction is patched with negative offsets and how the verifier handles infinite loop detection in eBPF programs. Systems running kernel versions 6.9 through 6.9.7 should prioritize this update immediately.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your current kernel version with `uname -r` and compare it against the affected range 6.9.0 to 6.9.7
  2. Step 2: Verify eBPF is enabled by checking `cat /boot/config-$(uname -r) | grep CONFIG_BPF` — if it returns 'CONFIG_BPF=y', the kernel has eBPF support
  3. Step 3: Search kernel logs with `dmesg | grep -i 'may_goto\|bpf.*verifier'` to identify any recent eBPF verification failures or anomalies
  4. Step 4: After updating, confirm the new kernel version with `uname -r` and reboot if necessary with `sudo systemctl reboot`

FAQ

What is CVE-2024-42072?

This vulnerability contains two distinct eBPF verifier bugs: improper patching of may_goto instructions with negative offsets, and incorrect infinite loop detection that fails to prune malicious program states. An attacker with eBPF loading capability could craft a malicious program to bypass verification checks and achieve kernel privilege escalation.

Is CVE-2024-42072 being actively exploited?

No, this CVE is not listed on the CISA Known Exploited Vulnerabilities catalog and no public exploits are currently available, though the vulnerability was discovered through adversarial fuzzing.

What versions of Kernel are affected by CVE-2024-42072?

Linux kernel versions 6.9.0 through 6.9.7 are vulnerable. The fix is included in kernel 6.9.8 and later.

How do I check if my server is vulnerable to CVE-2024-42072?

Run `uname -r` to display your kernel version. If the output shows 6.9.x where x is less than 8, your system is vulnerable. Additionally confirm eBPF is enabled with `cat /boot/config-$(uname -r) | grep CONFIG_BPF`.

Does Defensia detect CVE-2024-42072?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server running versions 6.9.0 through 6.9.7, CVE-2024-42072 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-2024-38612CVSS 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-2024-38623CVSS 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-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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