# CVE-2024-26645: tracing: Ensure visibility when inserting an element into tracing_map

> A race condition in the Linux kernel tracing map insertion can cause duplicate entries and trigger a kernel warning, potentially leading to denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Mar 2024
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-58795, BELL-CVE-2024-26645, DEBIAN-CVE-2024-26645, GHSA-hwc8-wrmm-ch4w, UBUNTU-CVE-2024-26645

## What is CVE-2024-26645?

CVE-2024-26645 is a medium-severity vulnerability in Debian Debian Linux, published on 26 Mar 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

tracing: Ensure visibility when inserting an element into tracing_map

Running the following two commands in parallel on a multi-processor
AArch64 machine can sporadically produce an unexpected warning about
duplicate histogram entries:

 $ while true; do
     echo hist:key=id.syscall:val=hitcount > \
       /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger
     cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist
     sleep 0.001
   done
 $ stress-ng --sysbadaddr $(nproc)

The warning looks as follows:

[ 2911.172474] ------------[ cut here ]------------
[ 2911.173111] Duplicates detected: 1
[ 2911.173574] WARNING: CPU: 2 PID: 12247 at kernel/trace/tracing_map.c:983 tracing_map_sort_entries+0x3e0/0x408
[ 2911.174702] Modules linked in: iscsi_ibft(E) iscsi_boot_sysfs(E) rfkill(E) af_packet(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ena(E) tiny_power_button(E) qemu_fw_cfg(E) button(E) fuse(E) efi_pstore(E) ip_tables(E) x_tables(E) xfs(E) libcrc32c(E) aes_ce_blk(E) aes_ce_cipher(E) crct10dif_ce(E) polyval_ce(E) polyval_generic(E) ghash_ce(E) gf128mul(E) sm4_ce_gcm(E) sm4_ce_ccm(E) sm4_ce(E) sm4_ce_cipher(E) sm4(E) sm3_ce(E) sm3(E) sha3_ce(E) sha512_ce(E) sha512_arm64(E) sha2_ce(E) sha256_arm64(E) nvme(E) sha1_ce(E) nvme_core(E) nvme_auth(E) t10_pi(E) sg(E) scsi_mod(E) scsi_common(E) efivarfs(E)
[ 2911.174738] Unloaded tainted modules: cppc_cpufreq(E):1
[ 2911.180985] CPU: 2 PID: 12247 Comm: cat Kdump: loaded Tainted: G            E      6.7.0-default #2 1b58bbb22c97e4399dc09f92d309344f69c44a01
[ 2911.182398] Hardware name: Amazon EC2 c7g.8xlarge/, BIOS 1.0 11/1/2018
[ 2911.183208] pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 2911.184038] pc : tracing_map_sort_entries+0x3e0/0x408
[ 2911.184667] lr : tracing_map_sort_entries+0x3e0/0x408
[ 2911.185310] sp : ffff8000a1513900
[ 2911.185750] x29: ffff8000a1513900 x28: ffff0003f272fe80 x27: 0000000000000001
[ 2911.186600] x26: ffff0003f272fe80 x25: 0000000000000030 x24: 0000000000000008
[ 2911.187458] x23: ffff0003c5788000 x22: ffff0003c16710c8 x21: ffff80008017f180
[ 2911.188310] x20: ffff80008017f000 x19: ffff80008017f180 x18: ffffffffffffffff
[ 2911.189160] x17: 0000000000000000 x16: 0000000000000000 x15: ffff8000a15134b8
[ 2911.190015] x14: 0000000000000000 x13: 205d373432323154 x12: 5b5d313131333731
[ 2911.190844] x11: 00000000fffeffff x10: 00000000fffeffff x9 : ffffd1b78274a13c
[ 2911.191716] x8 : 000000000017ffe8 x7 : c0000000fffeffff x6 : 000000000057ffa8
[ 2911.192554] x5 : ffff0012f6c24ec0 x4 : 0000000000000000 x3 : ffff2e5b72b5d000
[ 2911.193404] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0003ff254480
[ 2911.194259] Call trace:
[ 2911.194626]  tracing_map_sort_entries+0x3e0/0x408
[ 2911.195220]  hist_show+0x124/0x800
[ 2911.195692]  seq_read_iter+0x1d4/0x4e8
[ 2911.196193]  seq_read+0xe8/0x138
[ 2911.196638]  vfs_read+0xc8/0x300
[ 2911.197078]  ksys_read+0x70/0x108
[ 2911.197534]  __arm64_sys_read+0x24/0x38
[ 2911.198046]  invoke_syscall+0x78/0x108
[ 2911.198553]  el0_svc_common.constprop.0+0xd0/0xf8
[ 2911.199157]  do_el0_svc+0x28/0x40
[ 2911.199613]  el0_svc+0x40/0x178
[ 2911.200048]  el0t_64_sync_handler+0x13c/0x158
[ 2911.200621]  el0t_64_sync+0x1a8/0x1b0
[ 2911.201115] ---[ end trace 0000000000000000 ]---

The problem appears to be caused by CPU reordering of writes issued from
__tracing_map_insert().

The check for the presence of an element with a given key in this
function is:

 val = READ_ONCE(entry->val);
 if (val && keys_match(key, val->key, map->key_size)) ...

The write of a new entry is:

 elt = get_free_elt(map);
 memcpy(elt->key, key, map->key_size);
 entry->val = elt;

The "memcpy(elt->key, key, map->key_size);" and "entry->val = elt;"
stores may become visible in the reversed order on another CPU. This
second CPU might then incorrectly determine that a new key doesn't match
an already present val->key and subse
---truncated---

## Which versions are affected by CVE-2024-26645?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2024-26645?

Apply the vendor's patch.

## Is CVE-2024-26645 being exploited?

There is no known exploitation of CVE-2024-26645 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
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- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-26645 and fix it if it is affected.

What it is: CVE-2024-26645 is a medium-severity vulnerability in Debian Debian Linux, published on 26 Mar 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-26645 in the wild and no public exploit code.

Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-26645/ (Markdown: https://insights.sbomify.com/CVE-2024-26645/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26645
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26645
- OSV: https://osv.dev/vulnerability/CVE-2024-26645

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26645/
Summaries are generated and may contain mistakes; the official description above is the record.