# CVE-2024-41045: bpf: Defer work in bpf_timer_cancel_and_free CVE-2024-41045 is fixed in 22 products on 1 platform, first by DEBIAN-CVE-2024-41045, released July 29, 2024. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2024-41045 - Priority: High - CVSS: 7.8 (Moderate) - EPSS: 0.0029 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Jul 29, 2024 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-41045 ## Description In the Linux kernel, the following vulnerability has been resolved: bpf: Defer work in bpf_timer_cancel_and_free Currently, the same case as previous patch (two timer callbacks trying to cancel each other) can be invoked through bpf_map_update_elem as well, or more precisely, freeing map elements containing timers. Since this relies on hrtimer_cancel as well, it is prone to the same deadlock situation as the previous patch. It would be sufficient to use hrtimer_try_to_cancel to fix this problem, as the timer cannot be enqueued after async_cancel_and_free. Once async_cancel_and_free has been done, the timer must be reinitialized before it can be armed again. The callback running in parallel trying to arm the timer will fail, and freeing bpf_hrtimer without waiting is sufficient (given kfree_rcu), and bpf_timer_cb will return HRTIMER_NORESTART, preventing the timer from being rearmed again. However, there exists a UAF scenario where the callback arms the timer before entering this function, such that if cancellation fails (due to timer callback invoking this routine, or the target timer callback running concurrently). In such a case, if the timer expiration is significantly far in the future, the RCU grace period expiration happening before it will free the bpf_hrtimer state and along with it the struct hrtimer, that is enqueued. Hence, it is clear cancellation needs to occur after async_cancel_and_free, and yet it cannot be done inline due to deadlock issues. We thus modify bpf_timer_cancel_and_free to defer work to the global workqueue, adding a work_struct alongside rcu_head (both used at _different_ points of time, so can share space). Update existing code comments to reflect the new state of affairs. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | dtb-aarch64 opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-64kb opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-64kb sles 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-azure opensuse-leap 15.6 | 6.4.0-150600.8.11.1 | [SUSE-SU-2024:3194-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3194-1.md) | Sep 10, 2024 | | Linux | kernel-azure sles 15.6 | 6.4.0-150600.8.11.1 | [SUSE-SU-2024:3194-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3194-1.md) | Sep 10, 2024 | | Linux | kernel-debug opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-default opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-default sles 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-default-base opensuse-leap 15.6 | 6.4.0-150600.23.22.1.150600.12.8.3 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-default-base sles 15.6 | 6.4.0-150600.23.22.1.150600.12.8.3 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-docs opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-docs sles 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-kvmsmall opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-livepatch-SLE15-SP6-RT_Update_2 sles 15.6 | 1-150600.1.3.2 | [SUSE-SU-2024:3195-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3195-1.md) | Sep 10, 2024 | | Linux | kernel-livepatch-SLE15-SP6_Update_4 sles 15.6 | 1-150600.13.3.3 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-obs-build opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-obs-build sles 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-obs-qa opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-rt opensuse-leap 15.6 | 6.4.0-150600.10.8.3 | [SUSE-SU-2024:3195-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3195-1.md) | Sep 10, 2024 | | Linux | kernel-rt_debug opensuse-leap 15.6 | 6.4.0-150600.10.8.3 | [SUSE-SU-2024:3195-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3195-1.md) | Sep 10, 2024 | | Linux | kernel-source opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-source sles 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-source-azure opensuse-leap 15.6 | 6.4.0-150600.8.11.1 | [SUSE-SU-2024:3194-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3194-1.md) | Sep 10, 2024 | | Linux | kernel-source-azure sles 15.6 | 6.4.0-150600.8.11.1 | [SUSE-SU-2024:3194-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3194-1.md) | Sep 10, 2024 | | Linux | kernel-source-rt opensuse-leap 15.6 | 6.4.0-150600.10.8.3 | [SUSE-SU-2024:3195-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3195-1.md) | Sep 10, 2024 | | Linux | kernel-syms opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-syms sles 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-syms-azure opensuse-leap 15.6 | 6.4.0-150600.8.11.1 | [SUSE-SU-2024:3194-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3194-1.md) | Sep 10, 2024 | | Linux | kernel-syms-azure sles 15.6 | 6.4.0-150600.8.11.1 | [SUSE-SU-2024:3194-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3194-1.md) | Sep 10, 2024 | | Linux | kernel-syms-rt opensuse-leap 15.6 | 6.4.0-150600.10.8.1 | [SUSE-SU-2024:3195-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3195-1.md) | Sep 10, 2024 | | Linux | kernel-zfcpdump opensuse-leap 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | kernel-zfcpdump sles 15.6 | 6.4.0-150600.23.22.1 | [SUSE-SU-2024:3383-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3383-1.md) | Sep 23, 2024 | | Linux | linux Debian 13.5 (trixie) | 6.9.10-1 | [DEBIAN-CVE-2024-41045](https://patchblox.com/security/data/fix/linux/debian-cve-2024-41045.md) | Jul 29, 2024 | | Linux | linux Debian 14 | 6.9.10-1 | [DEBIAN-CVE-2024-41045](https://patchblox.com/security/data/fix/linux/debian-cve-2024-41045.md) | Jul 29, 2024 | --- Data as of 2026-11-09T07:25:28Z UTC. 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