CVE intelligence and bounded remediation

CVE-2021-47418 — Linux Linux Kernel security vulnerability

Medium CVSS 5.5

In the Linux kernel, the following vulnerability has been resolved: net_sched: fix NULL deref in fifo_set_limit() syzbot reported another NULL deref in fifo_set_limit() [1] I could repro the issue with : unshare -n tc qd add dev lo root handle 1:0 tbf limit 200000 burst 70000 rate 100Mbit tc qd replace dev lo parent 1:0 pfifo_fast tc qd change dev lo root handle 1:0 tbf limit 300000 burst 70000 rate 100Mbit pfifo_fast does not have a change() operation. Make fifo_set_limit() more robust about this. [1] BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 1cf99067 P4D 1cf99067 PUD 7ca49067 PMD 0 Oops: 0010 [#1] PREEMPT SMP KASAN CPU: 1 PID: 14443 Comm: syz-executor959 Not tainted 5.15.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:0x0 Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. RSP: 0018:ffffc9000e2f7310 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffffffff8d6ecc00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff888024c27910 RDI: ffff888071e34000 RBP: ffff888071e34000 R08: 0000000000000001 R09: ffffffff8fcfb947 R10: 0000000000000001 R11: 0000000000000000 R12: ffff888024c279…

Severity
Medium
CVSS
5.5 (3.1)
Published
2024-05-21
CISA KEV
Not currently listed
Ecosystem
linux/kernel
Weaknesses
CWE-476

Affected products

  • linux / linux_kernel
  • linux / linux_kernel / 5.15

Showing 2 representative product identities from 11 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Buffer bounds, memory safety, and memory corruption

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify affected native-code versions, build flags, architectures, parsers, codecs, drivers, and input paths in all shipped artifacts.
  • Determine whether untrusted data reaches the affected routine and the process privilege, sandbox, and network exposure.
  • Confirm statically linked, vendored, firmware, and platform-provided copies, not only package-manager records.

Remediate safely

  • Apply the maintained upstream correction or replace the affected component, then rebuild every dependent artifact from clean inputs.
  • Adopt bounds-checked interfaces, validated sizes and integer conversions, clear ownership, and memory-safe components where practical.
  • Enable supported compiler and runtime hardening and add sanitized tests and fuzz regression seeds derived from non-weaponized fixtures.

Authoritative sources

Complete CVE record and remediation plan

The detailed catalog view below loads this exact record, its source evidence, and the full seven-phase agentic change plan.