# CVE-2024-49926: rcu-tasks: Fix access non-existent percpu rtpcp variable in rcu_tasks_need_gpcb() CVE-2024-49926 is fixed in 22 products on 1 platform, first by DEBIAN-CVE-2024-49926, released October 21, 2024. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2024-49926 - Priority: Routine - CVSS: 5.5 (Moderate) - EPSS: 0.0024 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Oct 21, 2024 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-49926 ## Description In the Linux kernel, the following vulnerability has been resolved: rcu-tasks: Fix access non-existent percpu rtpcp variable in rcu_tasks_need_gpcb() For kernels built with CONFIG_FORCE_NR_CPUS=y, the nr_cpu_ids is defined as NR_CPUS instead of the number of possible cpus, this will cause the following system panic: smpboot: Allowing 4 CPUs, 0 hotplug CPUs ... setup_percpu: NR_CPUS:512 nr_cpumask_bits:512 nr_cpu_ids:512 nr_node_ids:1 ... BUG: unable to handle page fault for address: ffffffff9911c8c8 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 15 Comm: rcu_tasks_trace Tainted: G W 6.6.21 #1 5dc7acf91a5e8e9ac9dcfc35bee0245691283ea6 RIP: 0010:rcu_tasks_need_gpcb+0x25d/0x2c0 RSP: 0018:ffffa371c00a3e60 EFLAGS: 00010082 CR2: ffffffff9911c8c8 CR3: 000000040fa20005 CR4: 00000000001706f0 Call Trace: ? __die+0x23/0x80 ? page_fault_oops+0xa4/0x180 ? exc_page_fault+0x152/0x180 ? asm_exc_page_fault+0x26/0x40 ? rcu_tasks_need_gpcb+0x25d/0x2c0 ? __pfx_rcu_tasks_kthread+0x40/0x40 rcu_tasks_one_gp+0x69/0x180 rcu_tasks_kthread+0x94/0xc0 kthread+0xe8/0x140 ? __pfx_kthread+0x40/0x40 ret_from_fork+0x34/0x80 ? __pfx_kthread+0x40/0x40 ret_from_fork_asm+0x1b/0x80 Considering that there may be holes in the CPU numbers, use the maximum possible cpu number, instead of nr_cpu_ids, for configuring enqueue and dequeue limits. [ neeraj.upadhyay: Fix htmldocs build error reported by Stephen Rothwell ] ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | bpftool-debuginfo amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-debuginfo amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-debuginfo-common-aarch64 amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-debuginfo-common-x86_64 amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-devel amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-headers amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-libbpf amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-libbpf-devel amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-libbpf-static amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-livepatch-6.1.124-134.200 amzn 2023 | 1.0-0.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-modules-extra amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-modules-extra-common amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-tools amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-tools-debuginfo amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | kernel-tools-devel amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | linux Debian 13.5 (trixie) | 6.11.4-1 | [DEBIAN-CVE-2024-49926](https://patchblox.com/security/data/fix/linux/debian-cve-2024-49926.md) | Oct 21, 2024 | | Linux | linux Debian 14 | 6.11.4-1 | [DEBIAN-CVE-2024-49926](https://patchblox.com/security/data/fix/linux/debian-cve-2024-49926.md) | Oct 21, 2024 | | Linux | perf amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | perf-debuginfo amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | python3-perf amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | | Linux | python3-perf-debuginfo amzn 2023 | 6.1.124-134.200.amzn2023 | [ALAS2023-2025-809](https://patchblox.com/security/data/fix/linux/alas2023-2025-809.md) | Jan 21, 2025 | --- Data as of 2026-11-09T01:18:40Z UTC. 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