{"id":"CVE-2024-44991","state":"PUBLISHED","title":"tcp: prevent concurrent execution of tcp_sk_exit_batch","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: prevent concurrent execution of tcp_sk_exit_batch\n\nIts possible that two threads call tcp_sk_exit_batch() concurrently,\nonce from the cleanup_net workqueue, once from a task that failed to clone\na new netns.  In the latter case, error unwinding calls the exit handlers\nin reverse order for the 'failed' netns.\n\ntcp_sk_exit_batch() calls tcp_twsk_purge().\nProblem is that since commit b099ce2602d8 (\"net: Batch inet_twsk_purge\"),\nthis function picks up twsk in any dying netns, not just the one passed\nin via exit_batch list.\n\nThis means that the error unwind of setup_net() can \"steal\" and destroy\ntimewait sockets belonging to the exiting netns.\n\nThis allows the netns exit worker to proceed to call\n\nWARN_ON_ONCE(!refcount_dec_and_test(&net->ipv4.tcp_death_row.tw_refcount));\n\nwithout the expected 1 -> 0 transition, which then splats.\n\nAt same time, error unwind path that is also running inet_twsk_purge()\nwill splat as well:\n\nWARNING: .. at lib/refcount.c:31 refcount_warn_saturate+0x1ed/0x210\n...\n refcount_dec include/linux/refcount.h:351 [inline]\n inet_twsk_kill+0x758/0x9c0 net/ipv4/inet_timewait_sock.c:70\n inet_twsk_deschedule_put net/ipv4/inet_timewait_sock.c:221\n inet_twsk_purge+0x725/0x890 net/ipv4/inet_timewait_sock.c:304\n tcp_sk_exit_batch+0x1c/0x170 net/ipv4/tcp_ipv4.c:3522\n ops_exit_list+0x128/0x180 net/core/net_namespace.c:178\n setup_net+0x714/0xb40 net/core/net_namespace.c:375\n copy_net_ns+0x2f0/0x670 net/core/net_namespace.c:508\n create_new_namespaces+0x3ea/0xb10 kernel/nsproxy.c:110\n\n... because refcount_dec() of tw_refcount unexpectedly dropped to 0.\n\nThis doesn't seem like an actual bug (no tw sockets got lost and I don't\nsee a use-after-free) but as erroneous trigger of debug check.\n\nAdd a mutex to force strict ordering: the task that calls tcp_twsk_purge()\nblocks other task from doing final _dec_and_test before mutex-owner has\nremoved all tw sockets of dying netns.","publishedAt":"2024-09-04T19:54:38.206Z","updatedAt":"2026-05-11T20:33:21.068Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8","status":"affected","lessThan":"e3d9de3742f4d5c47ae35f888d3023a5b54fcd2f","versionType":"git"},{"version":"e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8","status":"affected","lessThan":"99580ae890ec8bd98b21a2a9c6668f8f1555b62e","versionType":"git"},{"version":"e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8","status":"affected","lessThan":"f6fd2dbf584a4047ba88d1369ff91c9851261ec1","versionType":"git"},{"version":"e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8","status":"affected","lessThan":"565d121b69980637f040eb4d84289869cdaabedf","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp_ipv4.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.1","versionType":"semver"},{"version":"6.1.107","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.48","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.10.7","status":"unaffected","lessThanOrEqual":"6.10.*","versionType":"semver"},{"version":"6.11","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp_ipv4.c"]}],"references":["https://git.kernel.org/stable/c/e3d9de3742f4d5c47ae35f888d3023a5b54fcd2f","https://git.kernel.org/stable/c/99580ae890ec8bd98b21a2a9c6668f8f1555b62e","https://git.kernel.org/stable/c/f6fd2dbf584a4047ba88d1369ff91c9851261ec1","https://git.kernel.org/stable/c/565d121b69980637f040eb4d84289869cdaabedf","https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:07:47.831Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2024/44xxx/CVE-2024-44991.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2024-44991","state":"PUBLISHED","datePublished":"2024-09-04T19:54:38.206Z","dateUpdated":"2026-05-11T20:33:21.068Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-08-21T05:34:56.671Z"},"containers":{"cna":{"title":"tcp: prevent concurrent execution of tcp_sk_exit_batch","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: prevent concurrent execution of tcp_sk_exit_batch\n\nIts possible that two threads call tcp_sk_exit_batch() concurrently,\nonce from the cleanup_net workqueue, once from a task that failed to clone\na new netns.  In the latter case, error unwinding calls the exit handlers\nin reverse order for the 'failed' netns.\n\ntcp_sk_exit_batch() calls tcp_twsk_purge().\nProblem is that since commit b099ce2602d8 (\"net: Batch inet_twsk_purge\"),\nthis function picks up twsk in any dying netns, not just the one passed\nin via exit_batch list.\n\nThis means that the error unwind of setup_net() can \"steal\" and destroy\ntimewait sockets belonging to the exiting netns.\n\nThis allows the netns exit worker to proceed to call\n\nWARN_ON_ONCE(!refcount_dec_and_test(&net->ipv4.tcp_death_row.tw_refcount));\n\nwithout the expected 1 -> 0 transition, which then splats.\n\nAt same time, error unwind path that is also running inet_twsk_purge()\nwill splat as well:\n\nWARNING: .. at lib/refcount.c:31 refcount_warn_saturate+0x1ed/0x210\n...\n refcount_dec include/linux/refcount.h:351 [inline]\n inet_twsk_kill+0x758/0x9c0 net/ipv4/inet_timewait_sock.c:70\n inet_twsk_deschedule_put net/ipv4/inet_timewait_sock.c:221\n inet_twsk_purge+0x725/0x890 net/ipv4/inet_timewait_sock.c:304\n tcp_sk_exit_batch+0x1c/0x170 net/ipv4/tcp_ipv4.c:3522\n ops_exit_list+0x128/0x180 net/core/net_namespace.c:178\n setup_net+0x714/0xb40 net/core/net_namespace.c:375\n copy_net_ns+0x2f0/0x670 net/core/net_namespace.c:508\n create_new_namespaces+0x3ea/0xb10 kernel/nsproxy.c:110\n\n... because refcount_dec() of tw_refcount unexpectedly dropped to 0.\n\nThis doesn't seem like an actual bug (no tw sockets got lost and I don't\nsee a use-after-free) but as erroneous trigger of debug check.\n\nAdd a mutex to force strict ordering: the task that calls tcp_twsk_purge()\nblocks other task from doing final _dec_and_test before mutex-owner has\nremoved all tw sockets of dying netns."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8","status":"affected","lessThan":"e3d9de3742f4d5c47ae35f888d3023a5b54fcd2f","versionType":"git"},{"version":"e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8","status":"affected","lessThan":"99580ae890ec8bd98b21a2a9c6668f8f1555b62e","versionType":"git"},{"version":"e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8","status":"affected","lessThan":"f6fd2dbf584a4047ba88d1369ff91c9851261ec1","versionType":"git"},{"version":"e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8","status":"affected","lessThan":"565d121b69980637f040eb4d84289869cdaabedf","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp_ipv4.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.1","versionType":"semver"},{"version":"6.1.107","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.48","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.10.7","status":"unaffected","lessThanOrEqual":"6.10.*","versionType":"semver"},{"version":"6.11","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/tcp_ipv4.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/e3d9de3742f4d5c47ae35f888d3023a5b54fcd2f"},{"url":"https://git.kernel.org/stable/c/99580ae890ec8bd98b21a2a9c6668f8f1555b62e"},{"url":"https://git.kernel.org/stable/c/f6fd2dbf584a4047ba88d1369ff91c9851261ec1"},{"url":"https://git.kernel.org/stable/c/565d121b69980637f040eb4d84289869cdaabedf"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T20:33:21.068Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.1.107"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.6.48"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.10.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.11"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2024-09-04T20:19:40.169819Z","id":"CVE-2024-44991","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2024-09-04T20:21:39.348Z"}},{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T22:14:48.281Z"}}]}}}