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

bpf: Wait for an RCU tasks grace period before freeing trampoline progs

When a prog is detached from a trampoline, it is freed after an RCU
grace period, or an RCU tasks trace one if it is sleepable. This covers
the tasks that are running the prog, since the prog's enter helper takes
the matching read lock before the prog is called. On a preemptible
kernel, it doesn't cover a task that was preempted in the trampoline
just before the enter helper. That task holds no lock yet, and it calls
the prog after it was freed:

BUG: KASAN: vmalloc-out-of-bounds in __bpf_prog_enter_recur+0x3a5/0x3f0
Read of size 8 at addr ffffc90000055040 by task candidate/110
CPU: 1 UID: 0 PID: 110 Comm: candidate Not tainted 7.3.0-rc2-00014-g15071f2a1263-dirty #2 PREEMPT(full)
Call Trace:
<TASK>
__bpf_prog_enter_recur+0x3a5/0x3f0
bpf_trampoline_6442509193+0x37/0xf1
__x64_sys_futex+0x9/0x410
do_syscall_64+0xb0/0x530
...

Wait for an RCU tasks grace period before the existing one when freeing
a prog that was linked to a trampoline. An RCU tasks grace period only
ends once the tasks that were preempted have run again, and
bpf_tramp_image_put() already relies on it to free the image. It doesn't
wait for tasks that sleep in the trampoline, the next commit takes care
of those.

Only progs that were linked to a trampoline can be called this way, so
bpf_trampoline_add_prog() marks them and other progs are still freed as
before.
Published: 2026-10-18
Score: n/a
EPSS: n/a
KEV: No
Impact: Kernel memory corruption potentially leading to a crash
Action: Patch Immediately
AI Analysis

Impact

The vulnerability arises from the Linux kernel freeing a BPF trampoline program after a partial RCU grace period that does not cover preempted tasks. This premature deallocation leads to a use‑after‑free that manifests as an out‑of‑bounds read error reported by KASAN. Based on the description, it is inferred that the memory corruption can cause a kernel crash; however, privilege escalation is not explicitly stated in the advisory.

Affected Systems

The identified affected vendor/product is Linux:Linux, indicating that all Linux kernel builds are potentially impacted. The input does not list specific version numbers, so it is inferred that the defect exists in the kernel tree prior to the commit referenced in the advisory.

Risk and Exploitability

The CVSS and EPSS scores are not disclosed in the advisory. The nature of the flaw—use‑after‑free and out‑of‑bounds read—suggests a high‑severity issue; based on the description, it is inferred that the CVSS score would be high. An attacker who can load eBPF programs may trigger the fault locally, potentially creating a kernel crash; the advisory does not confirm any active exploit. The flaw is not listed in the CISA KEV catalog at present.

Generated by OpenCVE AI on October 18, 2026 at 21:32 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade the Linux kernel to a version that incorporates the patch adding a full RCU grace period before freeing trampoline programs.
  • Check for and apply vendor security patches or available kernel updates as soon as they are released.
  • Monitor system logs for KASAN or Oops messages indicating memory corruption, and patch as soon as a stable release is available.

Generated by OpenCVE AI on October 18, 2026 at 21:32 UTC.

Tracking

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Advisories

No advisories yet.

History

Sun, 18 Oct 2026 22:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-238
CWE-416

Sun, 18 Oct 2026 16:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: bpf: Wait for an RCU tasks grace period before freeing trampoline progs When a prog is detached from a trampoline, it is freed after an RCU grace period, or an RCU tasks trace one if it is sleepable. This covers the tasks that are running the prog, since the prog's enter helper takes the matching read lock before the prog is called. On a preemptible kernel, it doesn't cover a task that was preempted in the trampoline just before the enter helper. That task holds no lock yet, and it calls the prog after it was freed: BUG: KASAN: vmalloc-out-of-bounds in __bpf_prog_enter_recur+0x3a5/0x3f0 Read of size 8 at addr ffffc90000055040 by task candidate/110 CPU: 1 UID: 0 PID: 110 Comm: candidate Not tainted 7.3.0-rc2-00014-g15071f2a1263-dirty #2 PREEMPT(full) Call Trace: <TASK> __bpf_prog_enter_recur+0x3a5/0x3f0 bpf_trampoline_6442509193+0x37/0xf1 __x64_sys_futex+0x9/0x410 do_syscall_64+0xb0/0x530 ... Wait for an RCU tasks grace period before the existing one when freeing a prog that was linked to a trampoline. An RCU tasks grace period only ends once the tasks that were preempted have run again, and bpf_tramp_image_put() already relies on it to free the image. It doesn't wait for tasks that sleep in the trampoline, the next commit takes care of those. Only progs that were linked to a trampoline can be called this way, so bpf_trampoline_add_prog() marks them and other progs are still freed as before.
Title bpf: Wait for an RCU tasks grace period before freeing trampoline progs
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-18T15:48:46.223Z

Reserved: 2026-09-25T10:25:14.370Z

Link: CVE-2026-98800

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-18T16:17:34.030

Modified: 2026-10-18T16:17:34.030

Link: CVE-2026-98800

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-18T21:45:05Z

Weaknesses
  • CWE-238

    Improper Handling of Incomplete Structural Elements

  • CWE-416

    Use After Free