{"api_version":"1","generated_at":"2026-10-08T13:53:40+00:00","cve":"CVE-2026-98276","urls":{"html":"https://cve.report/CVE-2026-98276","api":"https://cve.report/api/cve/CVE-2026-98276.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-98276","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-98276"},"summary":{"title":"net: lock the socket in sock_gettstamp()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: lock the socket in sock_gettstamp()\n\nsk->sk_flags must only be changed while holding the socket lock,\nbecause sock_set_flag() and sock_reset_flag() use non atomic\noperations (__set_bit() and __clear_bit()).\n\nsock_gettstamp() is one of the last places where a bit of sk->sk_flags\nis changed from a syscall without owning the socket lock, through\nsock_enable_timestamp(sk, SOCK_TIMESTAMP).\n\nsk_set_memalloc() and sk_clear_memalloc() also change sk->sk_flags\nwithout the socket lock, but their callers (nbd, iscsi_tcp, nvme-tcp,\nsunrpc, wireguard) need a careful audit, this will be addressed in a\nseparate patch.\n\nJungwoo Lee and Wongi Lee reported an UDP socket use-after-free\ncaused by this bug: a SIOCGSTAMPNS_NEW ioctl racing with bind()\ncan cancel the SOCK_RCU_FREE bit that udp_lib_get_port() just set,\nbecause both threads perform a read-modify-write on the same word.\n\n  CPU 0 (bind)                        CPU 1 (SIOCGSTAMPNS_NEW)\n  --------------------------------    ----------------------------\n  read sk_flags = F                   read sk_flags = F\n  compute F | BIT(SOCK_RCU_FREE)      compute F | BIT(SOCK_TIMESTAMP)\n  store F | BIT(SOCK_RCU_FREE)\n  sk_add_node_rcu(sk, ...)\n                                      store F | BIT(SOCK_TIMESTAMP)\n\nAfter the lost update, SOCK_RCU_FREE is clear while the socket is\nvisible to lockless UDP receive lookups. sk_destruct() then frees\nthe socket immediately instead of waiting for a RCU grace period,\nwhile the receive path still holds a reference-less pointer to it:\n\n BUG: KASAN: slab-use-after-free in ipv4_pktinfo_prepare+0x30/0x410\n Read of size 8 at addr ffff888008806610 by task exploit/207\n CPU: 0 UID: 1000 PID: 207 Comm: exploit Not tainted 6.12.95+ #1\n  ipv4_pktinfo_prepare+0x30/0x410\n  udp_queue_rcv_one_skb+0x51c/0x1180\n  udp_unicast_rcv_skb+0x109/0x350\n  ip_protocol_deliver_rcu+0x14b/0x310\n  ip_local_deliver_finish+0x29d/0x390\n  ip_local_deliver+0x24d/0x2a0\n\nOnly grab the socket lock when SOCK_TIMESTAMP has to be set,\nto keep the common case lockless.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-06 09:18:17","updated_at":"2026-10-07 07:17:07"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/88c804847dd87dc613b771b392ccecdb94725032","name":"https://git.kernel.org/stable/c/88c804847dd87dc613b771b392ccecdb94725032","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9ed55f3dbef4f4adfe65eb03b0c35c53229a8490","name":"https://git.kernel.org/stable/c/9ed55f3dbef4f4adfe65eb03b0c35c53229a8490","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/899650bbf985b7bfd2a7b808357df9b16e6d6959","name":"https://git.kernel.org/stable/c/899650bbf985b7bfd2a7b808357df9b16e6d6959","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/d9f96bc2d822501f84d1caa6275a2c6b316ca2c4","name":"https://git.kernel.org/stable/c/d9f96bc2d822501f84d1caa6275a2c6b316ca2c4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f","name":"https://git.kernel.org/stable/c/17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/18899e2e4023369a8f7739c2255a59a9748d8d17","name":"https://git.kernel.org/stable/c/18899e2e4023369a8f7739c2255a59a9748d8d17","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1f73253add8365d0dad0a4f421acaa8c21d20cef","name":"https://git.kernel.org/stable/c/1f73253add8365d0dad0a4f421acaa8c21d20cef","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3b12d3967e96f1b7b977d9fc352ae29a1b299a82","name":"https://git.kernel.org/stable/c/3b12d3967e96f1b7b977d9fc352ae29a1b299a82","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-98276","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98276","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 18899e2e4023369a8f7739c2255a59a9748d8d17 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 88c804847dd87dc613b771b392ccecdb94725032 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 3b12d3967e96f1b7b977d9fc352ae29a1b299a82 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 1f73253add8365d0dad0a4f421acaa8c21d20cef git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 d9f96bc2d822501f84d1caa6275a2c6b316ca2c4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 899650bbf985b7bfd2a7b808357df9b16e6d6959 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 9ed55f3dbef4f4adfe65eb03b0c35c53229a8490 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.12","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.12 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.271 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.222 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.189 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.158 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.112 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.54 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.8 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc4 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"98276","cve":"CVE-2026-98276","epss":"0.001840000","percentile":"0.073040000","score_date":"2026-10-06","updated_at":"2026-10-07 00:14:55"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/core/sock.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"18899e2e4023369a8f7739c2255a59a9748d8d17","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"88c804847dd87dc613b771b392ccecdb94725032","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"3b12d3967e96f1b7b977d9fc352ae29a1b299a82","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"1f73253add8365d0dad0a4f421acaa8c21d20cef","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"d9f96bc2d822501f84d1caa6275a2c6b316ca2c4","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"899650bbf985b7bfd2a7b808357df9b16e6d6959","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"9ed55f3dbef4f4adfe65eb03b0c35c53229a8490","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/core/sock.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.12"},{"lessThan":"2.6.12","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.271","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.222","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.189","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.158","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.112","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.54","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.8","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc4","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.271","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.222","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.189","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.158","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.112","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.54","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.8","versionStartIncluding":"2.6.12","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc4","versionStartIncluding":"2.6.12","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: lock the socket in sock_gettstamp()\n\nsk->sk_flags must only be changed while holding the socket lock,\nbecause sock_set_flag() and sock_reset_flag() use non atomic\noperations (__set_bit() and __clear_bit()).\n\nsock_gettstamp() is one of the last places where a bit of sk->sk_flags\nis changed from a syscall without owning the socket lock, through\nsock_enable_timestamp(sk, SOCK_TIMESTAMP).\n\nsk_set_memalloc() and sk_clear_memalloc() also change sk->sk_flags\nwithout the socket lock, but their callers (nbd, iscsi_tcp, nvme-tcp,\nsunrpc, wireguard) need a careful audit, this will be addressed in a\nseparate patch.\n\nJungwoo Lee and Wongi Lee reported an UDP socket use-after-free\ncaused by this bug: a SIOCGSTAMPNS_NEW ioctl racing with bind()\ncan cancel the SOCK_RCU_FREE bit that udp_lib_get_port() just set,\nbecause both threads perform a read-modify-write on the same word.\n\n  CPU 0 (bind)                        CPU 1 (SIOCGSTAMPNS_NEW)\n  --------------------------------    ----------------------------\n  read sk_flags = F                   read sk_flags = F\n  compute F | BIT(SOCK_RCU_FREE)      compute F | BIT(SOCK_TIMESTAMP)\n  store F | BIT(SOCK_RCU_FREE)\n  sk_add_node_rcu(sk, ...)\n                                      store F | BIT(SOCK_TIMESTAMP)\n\nAfter the lost update, SOCK_RCU_FREE is clear while the socket is\nvisible to lockless UDP receive lookups. sk_destruct() then frees\nthe socket immediately instead of waiting for a RCU grace period,\nwhile the receive path still holds a reference-less pointer to it:\n\n BUG: KASAN: slab-use-after-free in ipv4_pktinfo_prepare+0x30/0x410\n Read of size 8 at addr ffff888008806610 by task exploit/207\n CPU: 0 UID: 1000 PID: 207 Comm: exploit Not tainted 6.12.95+ #1\n  ipv4_pktinfo_prepare+0x30/0x410\n  udp_queue_rcv_one_skb+0x51c/0x1180\n  udp_unicast_rcv_skb+0x109/0x350\n  ip_protocol_deliver_rcu+0x14b/0x310\n  ip_local_deliver_finish+0x29d/0x390\n  ip_local_deliver+0x24d/0x2a0\n\nOnly grab the socket lock when SOCK_TIMESTAMP has to be set,\nto keep the common case lockless."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The lost update is caused by a local process racing the SIOCGSTAMP*/SIOCGSTAMPNS* ioctl (sock_ioctl -> sock_gettstamp -> sock_enable_timestamp) against bind() -> udp_lib_get_port() setting SOCK_RCU_FREE on its own UDP socket. No network message supplies the triggering state; remote packets only deliver into the already-corrupted socket.\nAC:L - The attacker owns both sides of the race: one thread calls bind(), another calls the timestamp ioctl on the same fd. It can create, bind and close sockets in a loop until the __set_bit read-modify-write on sk_flags loses SOCK_RCU_FREE, then send loopback UDP to hit the freed sock.\nPR:L - It only needs an ordinary AF_INET/AF_INET6 UDP socket. sock_ioctl's SIOCGSTAMP case and inet bind to an ephemeral or unprivileged port have no capability check, and the reporters reproduced it as UID 1000.\nUI:N - The attacker drives every step (socket creation, concurrent bind/ioctl, close, sending packets to its own port) with no action from any other user.\nS:U - The freed struct sock and the code that reads it are both in the same kernel; this is local kernel memory corruption that leads to privilege escalation inside one authority, with no VM or sandbox boundary crossed.\nC:H - With SOCK_RCU_FREE lost, sk_destruct frees the UDP struct sock immediately while lockless RCU lookups in udp_unicast_rcv_skb/udp_queue_rcv_one_skb still hold a pointer to it. A slab UAF of a struct sock can be reclaimed with sprayed data to leak kernel memory.\nI:H - The receive path operates on the freed sock: it queues skbs, updates counters and reads sk_prot/sk_filter-related fields. If the attacker reclaims the slab, these become writes into, and function-pointer use from, attacker-controlled memory, which is a path to control-flow hijack.\nA:H - Even when not exploited, the use-after-free in ipv4_pktinfo_prepare/udp_queue_rcv_one_skb (shown by KASAN) corrupts slab memory and can oops or panic the kernel."}]}],"providerMetadata":{"dateUpdated":"2026-10-07T06:49:51.156Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/18899e2e4023369a8f7739c2255a59a9748d8d17"},{"url":"https://git.kernel.org/stable/c/88c804847dd87dc613b771b392ccecdb94725032"},{"url":"https://git.kernel.org/stable/c/3b12d3967e96f1b7b977d9fc352ae29a1b299a82"},{"url":"https://git.kernel.org/stable/c/17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f"},{"url":"https://git.kernel.org/stable/c/1f73253add8365d0dad0a4f421acaa8c21d20cef"},{"url":"https://git.kernel.org/stable/c/d9f96bc2d822501f84d1caa6275a2c6b316ca2c4"},{"url":"https://git.kernel.org/stable/c/899650bbf985b7bfd2a7b808357df9b16e6d6959"},{"url":"https://git.kernel.org/stable/c/9ed55f3dbef4f4adfe65eb03b0c35c53229a8490"}],"title":"net: lock the socket in sock_gettstamp()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-98276","datePublished":"2026-10-06T08:45:36.837Z","dateReserved":"2026-09-25T10:25:14.334Z","dateUpdated":"2026-10-07T06:49:51.156Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-06 09:18:17","lastModifiedDate":"2026-10-07 07:17:07","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"98276","Ordinal":"1","Title":"net: lock the socket in sock_gettstamp()","CVE":"CVE-2026-98276","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"98276","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: lock the socket in sock_gettstamp()\n\nsk->sk_flags must only be changed while holding the socket lock,\nbecause sock_set_flag() and sock_reset_flag() use non atomic\noperations (__set_bit() and __clear_bit()).\n\nsock_gettstamp() is one of the last places where a bit of sk->sk_flags\nis changed from a syscall without owning the socket lock, through\nsock_enable_timestamp(sk, SOCK_TIMESTAMP).\n\nsk_set_memalloc() and sk_clear_memalloc() also change sk->sk_flags\nwithout the socket lock, but their callers (nbd, iscsi_tcp, nvme-tcp,\nsunrpc, wireguard) need a careful audit, this will be addressed in a\nseparate patch.\n\nJungwoo Lee and Wongi Lee reported an UDP socket use-after-free\ncaused by this bug: a SIOCGSTAMPNS_NEW ioctl racing with bind()\ncan cancel the SOCK_RCU_FREE bit that udp_lib_get_port() just set,\nbecause both threads perform a read-modify-write on the same word.\n\n  CPU 0 (bind)                        CPU 1 (SIOCGSTAMPNS_NEW)\n  --------------------------------    ----------------------------\n  read sk_flags = F                   read sk_flags = F\n  compute F | BIT(SOCK_RCU_FREE)      compute F | BIT(SOCK_TIMESTAMP)\n  store F | BIT(SOCK_RCU_FREE)\n  sk_add_node_rcu(sk, ...)\n                                      store F | BIT(SOCK_TIMESTAMP)\n\nAfter the lost update, SOCK_RCU_FREE is clear while the socket is\nvisible to lockless UDP receive lookups. sk_destruct() then frees\nthe socket immediately instead of waiting for a RCU grace period,\nwhile the receive path still holds a reference-less pointer to it:\n\n BUG: KASAN: slab-use-after-free in ipv4_pktinfo_prepare+0x30/0x410\n Read of size 8 at addr ffff888008806610 by task exploit/207\n CPU: 0 UID: 1000 PID: 207 Comm: exploit Not tainted 6.12.95+ #1\n  ipv4_pktinfo_prepare+0x30/0x410\n  udp_queue_rcv_one_skb+0x51c/0x1180\n  udp_unicast_rcv_skb+0x109/0x350\n  ip_protocol_deliver_rcu+0x14b/0x310\n  ip_local_deliver_finish+0x29d/0x390\n  ip_local_deliver+0x24d/0x2a0\n\nOnly grab the socket lock when SOCK_TIMESTAMP has to be set,\nto keep the common case lockless.","Type":"Description","Title":"net: lock the socket in sock_gettstamp()"}]}}}