medium CVSS 6.8

CVE-2024-36013·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix slab-use-after-free in l2cap_connect() Extend a critical section to prevent chan from early freeing. Also make the l2cap_connect() return type void. Nothing is using the returned value but it is ugly to return a potentially freed pointer. Making it void will help with backports because earlier kernels did use the return value. Now the compile will break for kernels where this patch is not a complete fix. Call stack summary: [use] l2cap_bredr_sig_cmd l2cap_connect ┌ mutex_lock(&conn->chan_lock); │ chan = pchan->ops->new_connection(pchan); <- alloc chan │ __l2cap_chan_add(conn, chan); │ l2cap_chan_hold(chan); │ list_add(&chan->list, &conn->chan_l); ... (1) └ mutex_unlock(&conn->chan_lock); chan->conf_state ... (4) <- use after free [free] l2cap_conn_del ┌ mutex_lock(&conn->chan_lock); │ foreach chan in conn->chan_l: ... (2) │ l2cap_chan_put(chan); │ l2cap_chan_destroy │ kfree(chan) ... (3) <- chan freed └ mutex_unlock(&conn->chan_lock); ================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read include/linux/instrumented.h:68 [inline] BUG: KASAN: slab-use-after-free in _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline] BUG: KASAN: slab-use-after-free in l2cap_connect+0xa67/0x11a0 net/bluetooth/l2cap_core.c:4260 Read of size 8 at addr ffff88810bf040a0 by task kworker/u3:1/311

Severity
medium
Software
Kernel
Fixed in
6.8.11
Published
2024-05-23

Affected versions

From: 6.7

Until: 6.8.11

Fixed in: 6.8.11

How to fix this CVE

Update your Linux kernel to version 6.8.11 or later to resolve this Bluetooth L2CAP memory safety issue. The vulnerability occurs when the kernel fails to properly protect a Bluetooth channel object from being freed while still in use, leading to a use-after-free condition. Applying this patch eliminates the race condition by extending the critical section that guards the channel lifecycle.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed kernel version: uname -r — verify it is 6.8.11 or later
  2. Confirm Bluetooth subsystem is loaded: lsmod | grep bluetooth — look for l2cap module presence
  3. Review kernel logs for KASAN warnings: sudo dmesg | grep -i 'slab-use-after-free\|l2cap_connect' — look for memory safety violations
  4. Verify patch application: grep -r 'l2cap_connect' /usr/src/linux-headers-$(uname -r)/net/bluetooth/ — confirm critical section extends around chan allocation and usage

FAQ

What is CVE-2024-36013?

This is a use-after-free vulnerability in the Linux kernel's Bluetooth L2CAP layer where a communication channel object could be freed prematurely while still being accessed, causing memory corruption and potential system instability.

Is CVE-2024-36013 being actively exploited?

No, this vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog and no public exploits are currently available.

What versions of Kernel are affected by CVE-2024-36013?

Linux kernel versions 6.7 through 6.8.10 are vulnerable; version 6.8.11 and later contain the fix.

How do I check if my server is vulnerable to CVE-2024-36013?

Run 'uname -r' to display your kernel version — if it shows 6.8.10 or earlier and 6.7.x, your system is vulnerable and requires immediate kernel update.

Does Defensia detect CVE-2024-36013?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2024-36013 will appear in your dashboard with remediation steps.

Related Kernel CVEs

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References

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