medium CVSS 6.3 EPSS <0.1%

CVE-2024-38544·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Fix seg fault in rxe_comp_queue_pkt In rxe_comp_queue_pkt() an incoming response packet skb is enqueued to the resp_pkts queue and then a decision is made whether to run the completer task inline or schedule it. Finally the skb is dereferenced to bump a 'hw' performance counter. This is wrong because if the completer task is already running in a separate thread it may have already processed the skb and freed it which can cause a seg fault. This has been observed infrequently in testing at high scale. This patch fixes this by changing the order of enqueuing the packet until after the counter is accessed.

Severity
medium
Software
Kernel
Fixed in
6.9.3
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 1% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Affected versions

From: 6.9

Until: 6.9.3

Fixed in: 6.9.3

How to fix this CVE

Update your Linux kernel to version 6.9.3 or later to resolve a race condition in the RDMA/rxe driver that can cause kernel segmentation faults. This vulnerability occurs when packet processing overlaps between threads, leading to use-after-free conditions. Apply the patch immediately on systems using kernel 6.9 through 6.9.2, particularly those with high-scale RDMA workloads.

sudo dnf update kernel kernel-devel kernel-headers

Defensia detects this vulnerability

How to check if you are affected

  1. Run `uname -r` to check your current kernel version; if it reports 6.9.0, 6.9.1, or 6.9.2, your system is vulnerable
  2. Check if RDMA/rxe driver is loaded with `lsmod | grep rdma` or `lsmod | grep rxe`; if present, the vulnerability surface is active
  3. Search kernel logs for segmentation faults related to rxe_comp_queue_pkt: `sudo dmesg | grep -i 'seg fault\|rxe_comp\|unable to handle kernel'`
  4. Verify the fix by confirming kernel version is 6.9.3 or later with `uname -r`, and check that no new kernel panic messages appear in `sudo journalctl -u kernel -n 50`

FAQ

What is CVE-2024-38544?

CVE-2024-38544 is a race condition in the Linux kernel's RDMA/rxe driver where a packet buffer may be dereferenced after being freed by a concurrent thread, causing kernel crashes. The vulnerability exists in the rxe_comp_queue_pkt() function where packet enqueueing and counter access operations were not properly sequenced.

Is CVE-2024-38544 being actively exploited?

No, CVE-2024-38544 is not listed as actively exploited by CISA and no public exploits are available. This is a reliability/stability issue rather than a security vulnerability that would allow unauthorized access or privilege escalation.

What versions of Kernel are affected by CVE-2024-38544?

Linux kernel versions 6.9.0 through 6.9.2 are vulnerable. The fix is included in kernel 6.9.3 and later stable releases.

How do I check if my server is vulnerable to CVE-2024-38544?

Run `uname -r` to see your kernel version. If it returns 6.9.0, 6.9.1, or 6.9.2 and you have RDMA/rxe in use, verify with `lsmod | grep rxe` or `ethtool -i ethX` to confirm RDMA interface presence.

Does Defensia detect CVE-2024-38544?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Linux kernel is installed on a monitored server, CVE-2024-38544 will appear in your dashboard with remediation steps.

Related Kernel CVEs

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References

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