{"id":"CVE-2023-53781","revision":"768f0b699d4f49048b2835b95673137b","records":[{"revision":"768f0b699d4f49048b2835b95673137b","observedAt":"2026-10-30T13:45:33.454+00:00","statement":{"source":"cve-program","id":"CVE-2023-53781","aliases":[],"title":"smc: Fix use-after-free in tcp_write_timer_handler().","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmc: Fix use-after-free in tcp_write_timer_handler().\n\nWith Eric's ref tracker, syzbot finally found a repro for\nuse-after-free in tcp_write_timer_handler() by kernel TCP\nsockets. [0]\n\nIf SMC creates a kernel socket in __smc_create(), the kernel\nsocket is supposed to be freed in smc_clcsock_release() by\ncalling sock_release() when we close() the parent SMC socket.\n\nHowever, at the end of smc_clcsock_release(), the kernel\nsocket's sk_state might not be TCP_CLOSE. This means that\nwe have not called inet_csk_destroy_sock() in __tcp_close()\nand have not stopped the TCP timers.\n\nThe kernel socket's TCP timers can be fired later, so we\nneed to hold a refcnt for net as we do for MPTCP subflows\nin mptcp_subflow_create_socket().\n\n[0]:\nleaked reference.\n sk_alloc (./include/net/net_namespace.h:335 net/core/sock.c:2108)\n inet_create (net/ipv4/af_inet.c:319 net/ipv4/af_inet.c:244)\n __sock_create (net/socket.c:1546)\n smc_create (net/smc/af_smc.c:3269 net/smc/af_smc.c:3284)\n __sock_create (net/socket.c:1546)\n __sys_socket (net/socket.c:1634 net/socket.c:1618 net/socket.c:1661)\n __x64_sys_socket (net/socket.c:1672)\n do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)\n entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)\n==================================================================\nBUG: KASAN: slab-use-after-free in tcp_write_timer_handler (net/ipv4/tcp_timer.c:378 net/ipv4/tcp_timer.c:624 net/ipv4/tcp_timer.c:594)\nRead of size 1 at addr ffff888052b65e0d by task syzrepro/18091\n\nCPU: 0 PID: 18091 Comm: syzrepro Tainted: G W 6.3.0-rc4-01174-gb5d54eb5899a #7\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.amzn2022.0.1 04/01/2014\nCall Trace:\n \n dump_stack_lvl (lib/dump_stack.c:107)\n print_report (mm/kasan/report.c:320 mm/kasan/report.c:430)\n kasan_report (mm/kasan/report.c:538)\n tcp_write_timer_handler (net/ipv4/tcp_timer.c:378 net/ipv4/tcp_timer.c:624 net/ipv4/tcp_timer.c:594)\n tcp_write_timer (./include/linux/spinlock.h:390 net/ipv4/tcp_timer.c:643)\n call_timer_fn (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/timer.h:127 kernel/time/timer.c:1701)\n __run_timers.part.0 (kernel/time/timer.c:1752 kernel/time/timer.c:2022)\n run_timer_softirq (kernel/time/timer.c:2037)\n __do_softirq (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/irq.h:142 kernel/softirq.c:572)\n __irq_exit_rcu (kernel/softirq.c:445 kernel/softirq.c:650)\n irq_exit_rcu (kernel/softirq.c:664)\n sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1107 (discriminator 14))\n ","state":0,"publishedAt":"2025-12-09T00:00:36.831+00:00","modifiedAt":"2026-10-30T12:17:35.78+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/smc/af_smc.c\"\n ],\n \"versions\": [\n {\n \"version\": \"ac7138746e14137a451f8539614cdd349153e0c0\",\n \"lessThan\": \"08f057bd1e559cdb388c77b18de3eea3d3d8cb24\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac7138746e14137a451f8539614cdd349153e0c0\",\n \"lessThan\": \"1cc41c8acfc1ee30b4868559058db97fa44b0137\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"ac7138746e14137a451f8539614cdd349153e0c0\",\n \"lessThan\": \"9744d2bf19762703704ecba885b7ac282c02eacf\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/smc/af_smc.c\"\n ],\n \"versions\": [\n {\n \"version\": \"4.11\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"4.11\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.191\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.2.12\",\n \"lessThanOrEqual\": \"6.2.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.3\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/08f057bd1e559cdb388c77b18de3eea3d3d8cb24","https://git.kernel.org/stable/c/1cc41c8acfc1ee30b4868559058db97fa44b0137","https://git.kernel.org/stable/c/9744d2bf19762703704ecba885b7ac282c02eacf"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2023-53781","license":"CVE Program Terms of Use","key":"cve-program:CVE-2023-53781","identifiers":["CVE-2023-53781"]},"retained":false,"historicalAffected":[]}],"coverage":[]}