# CVE-2024-44991: linux: In the Linux kernel, the following vulnerability has been resolved:  tcp: prevent concurrent execution of tcp_sk_exit...

CVE-2024-44991 is fixed in 47 products on 1 platform, first by DEBIAN-CVE-2024-44991, released September 4, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2024-44991
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0025
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 4, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  tcp: prevent concurrent execution of tcp_sk_exit_batch  Its possible that two threads call tcp_sk_exit_batch() concurrently, once from the cleanup_net workqueue, once from a task that failed to clone a new netns.  In the latter case, error unwinding calls the exit handlers in reverse order for the 'failed' netns.  tcp_sk_exit_batch() calls tcp_twsk_purge(). Problem is that since commit b099ce2602d8 ("net: Batch inet_twsk_purge"), this function picks up twsk in any dying netns, not just the one passed in via exit_batch list.  This means that the error unwind of setup_net() can "steal" and destroy timewait sockets belonging to the exiting netns.  This allows the netns exit worker to proceed to call  WARN_ON_ONCE(!refcount_dec_and_test(&net->ipv4.tcp_death_row.tw_refcount));  without the expected 1 -> 0 transition, which then splats.  At same time, error unwind path that is also running inet_twsk_purge() will splat as well:  WARNING: .. at lib/refcount.c:31 refcount_warn_saturate+0x1ed/0x210 ...  refcount_dec include/linux/refcount.h:351 [inline]  inet_twsk_kill+0x758/0x9c0 net/ipv4/inet_timewait_sock.c:70  inet_twsk_deschedule_put net/ipv4/inet_timewait_sock.c:221  inet_twsk_purge+0x725/0x890 net/ipv4/inet_timewait_sock.c:304  tcp_sk_exit_batch+0x1c/0x170 net/ipv4/tcp_ipv4.c:3522  ops_exit_list+0x128/0x180 net/core/net_namespace.c:178  setup_net+0x714/0xb40 net/core/net_namespace.c:375  copy_net_ns+0x2f0/0x670 net/core/net_namespace.c:508  create_new_namespaces+0x3ea/0xb10 kernel/nsproxy.c:110  ... because refcount_dec() of tw_refcount unexpectedly dropped to 0.  This doesn't seem like an actual bug (no tw sockets got lost and I don't see a use-after-free) but as erroneous trigger of debug check.  Add a mutex to force strict ordering: the task that calls tcp_twsk_purge() blocks other task from doing final _dec_and_test before mutex-owner has removed all tw sockets of dying netns.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | bpftool amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | bpftool-debuginfo amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | dtb-aarch64 opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-64kb opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-64kb sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-azure opensuse-leap 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 |
| Linux | kernel-azure sles 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 |
| Linux | kernel-coco sles 15.6 | 6.4.0-15061.6.coco15sp6.1 | [SUSE-SU-2024:3553-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3553-1.md) | Oct 8, 2024 |
| Linux | kernel-coco_debug sles 15.6 | 6.4.0-15061.6.coco15sp6.1 | [SUSE-SU-2024:3553-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3553-1.md) | Oct 8, 2024 |
| Linux | kernel-debug opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-debuginfo amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-debuginfo-common-aarch64 amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-debuginfo-common-x86_64 amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-default opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-default sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-default-base opensuse-leap 15.6 | 6.4.0-150600.23.25.1.150600.12.10.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-default-base sles 15.6 | 6.4.0-150600.23.25.1.150600.12.10.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-devel amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-docs opensuse-leap 15.6 | 6.4.0-150600.23.25.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-docs sles 15.6 | 6.4.0-150600.23.25.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-headers amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-kvmsmall opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-libbpf amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-libbpf-devel amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-libbpf-static amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-livepatch-6.1.109-118.189 amzn 2023 | 1.0-0.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-livepatch-SLE15-SP6-RT_Update_4 sles 15.6 | 1-150600.1.3.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 |
| Linux | kernel-livepatch-SLE15-SP6_Update_5 sles 15.6 | 1-150600.13.3.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-modules-extra amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-modules-extra-common amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-obs-build opensuse-leap 15.6 | 6.4.0-150600.23.25.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-obs-build sles 15.6 | 6.4.0-150600.23.25.2 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-obs-qa opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-rt opensuse-leap 15.6 | 6.4.0-150600.10.14.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 |
| Linux | kernel-rt_debug opensuse-leap 15.6 | 6.4.0-150600.10.14.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 |
| Linux | kernel-source opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-source sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-source-azure opensuse-leap 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 |
| Linux | kernel-source-azure sles 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 |
| Linux | kernel-source-coco sles 15.6 | 6.4.0-15061.6.coco15sp6.1 | [SUSE-SU-2024:3553-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3553-1.md) | Oct 8, 2024 |
| Linux | kernel-source-rt opensuse-leap 15.6 | 6.4.0-150600.10.14.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 |
| Linux | kernel-syms opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-syms sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-syms-azure opensuse-leap 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 |
| Linux | kernel-syms-azure sles 15.6 | 6.4.0-150600.8.14.1 | [SUSE-SU-2024:3551-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3551-1.md) | Oct 8, 2024 |
| Linux | kernel-syms-coco sles 15.6 | 6.4.0-15061.6.coco15sp6.1 | [SUSE-SU-2024:3553-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3553-1.md) | Oct 8, 2024 |
| Linux | kernel-syms-rt opensuse-leap 15.6 | 6.4.0-150600.10.14.1 | [SUSE-SU-2024:3564-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3564-1.md) | Oct 9, 2024 |
| Linux | kernel-tools amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-tools-debuginfo amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-tools-devel amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | kernel-zfcpdump opensuse-leap 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | kernel-zfcpdump sles 15.6 | 6.4.0-150600.23.25.1 | [SUSE-SU-2024:3561-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3561-1.md) | Oct 9, 2024 |
| Linux | linux Debian 12.15 (bookworm) | 6.1.112-1 | [DEBIAN-CVE-2024-44991](https://patchblox.com/security/data/fix/linux/debian-cve-2024-44991.md) | Sep 4, 2024 |
| Linux | linux Debian 13.5 (trixie) | 6.10.7-1 | [DEBIAN-CVE-2024-44991](https://patchblox.com/security/data/fix/linux/debian-cve-2024-44991.md) | Sep 4, 2024 |
| Linux | linux Debian 14 | 6.10.7-1 | [DEBIAN-CVE-2024-44991](https://patchblox.com/security/data/fix/linux/debian-cve-2024-44991.md) | Sep 4, 2024 |
| Linux | perf amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | perf-debuginfo amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | python3-perf amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |
| Linux | python3-perf-debuginfo amzn 2023 | 6.1.109-118.189.amzn2023 | [ALAS2023-2024-779](https://patchblox.com/security/data/fix/linux/alas2023-2024-779.md) | Dec 5, 2024 |

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