CVE-2023-53781 (GCVE-0-2023-53781)
Vulnerability from cvelistv5 – Published: 2025-12-09 00:00 – Updated: 2025-12-09 00:00
VLAI?
Title
smc: Fix use-after-free in tcp_write_timer_handler().
Summary
In the Linux kernel, the following vulnerability has been resolved:
smc: Fix use-after-free in tcp_write_timer_handler().
With Eric's ref tracker, syzbot finally found a repro for
use-after-free in tcp_write_timer_handler() by kernel TCP
sockets. [0]
If SMC creates a kernel socket in __smc_create(), the kernel
socket is supposed to be freed in smc_clcsock_release() by
calling sock_release() when we close() the parent SMC socket.
However, at the end of smc_clcsock_release(), the kernel
socket's sk_state might not be TCP_CLOSE. This means that
we have not called inet_csk_destroy_sock() in __tcp_close()
and have not stopped the TCP timers.
The kernel socket's TCP timers can be fired later, so we
need to hold a refcnt for net as we do for MPTCP subflows
in mptcp_subflow_create_socket().
[0]:
leaked reference.
sk_alloc (./include/net/net_namespace.h:335 net/core/sock.c:2108)
inet_create (net/ipv4/af_inet.c:319 net/ipv4/af_inet.c:244)
__sock_create (net/socket.c:1546)
smc_create (net/smc/af_smc.c:3269 net/smc/af_smc.c:3284)
__sock_create (net/socket.c:1546)
__sys_socket (net/socket.c:1634 net/socket.c:1618 net/socket.c:1661)
__x64_sys_socket (net/socket.c:1672)
do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)
==================================================================
BUG: 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)
Read of size 1 at addr ffff888052b65e0d by task syzrepro/18091
CPU: 0 PID: 18091 Comm: syzrepro Tainted: G W 6.3.0-rc4-01174-gb5d54eb5899a #7
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.amzn2022.0.1 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl (lib/dump_stack.c:107)
print_report (mm/kasan/report.c:320 mm/kasan/report.c:430)
kasan_report (mm/kasan/report.c:538)
tcp_write_timer_handler (net/ipv4/tcp_timer.c:378 net/ipv4/tcp_timer.c:624 net/ipv4/tcp_timer.c:594)
tcp_write_timer (./include/linux/spinlock.h:390 net/ipv4/tcp_timer.c:643)
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)
__run_timers.part.0 (kernel/time/timer.c:1752 kernel/time/timer.c:2022)
run_timer_softirq (kernel/time/timer.c:2037)
__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)
__irq_exit_rcu (kernel/softirq.c:445 kernel/softirq.c:650)
irq_exit_rcu (kernel/softirq.c:664)
sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1107 (discriminator 14))
</IRQ>
Severity ?
No CVSS data available.
Assigner
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/smc/af_smc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "1cc41c8acfc1ee30b4868559058db97fa44b0137",
"status": "affected",
"version": "ac7138746e14137a451f8539614cdd349153e0c0",
"versionType": "git"
},
{
"lessThan": "9744d2bf19762703704ecba885b7ac282c02eacf",
"status": "affected",
"version": "ac7138746e14137a451f8539614cdd349153e0c0",
"versionType": "git"
}
]
},
{
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"product": "Linux",
"programFiles": [
"net/smc/af_smc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.11"
},
{
"lessThan": "4.11",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.2.*",
"status": "unaffected",
"version": "6.2.12",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.2.12",
"versionStartIncluding": "4.11",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.3",
"versionStartIncluding": "4.11",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmc: Fix use-after-free in tcp_write_timer_handler().\n\nWith Eric\u0027s 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\u0027s 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\u0027s 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 \u003cIRQ\u003e\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 \u003c/IRQ\u003e"
}
],
"providerMetadata": {
"dateUpdated": "2025-12-09T00:00:36.831Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/1cc41c8acfc1ee30b4868559058db97fa44b0137"
},
{
"url": "https://git.kernel.org/stable/c/9744d2bf19762703704ecba885b7ac282c02eacf"
}
],
"title": "smc: Fix use-after-free in tcp_write_timer_handler().",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2023-53781",
"datePublished": "2025-12-09T00:00:36.831Z",
"dateReserved": "2025-12-08T23:58:35.272Z",
"dateUpdated": "2025-12-09T00:00:36.831Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2023-53781\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-09T01:16:49.280\",\"lastModified\":\"2025-12-09T18:37:13.640\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nsmc: Fix use-after-free in tcp_write_timer_handler().\\n\\nWith Eric\u0027s 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\u0027s 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\u0027s 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 \u003cIRQ\u003e\\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 \u003c/IRQ\u003e\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1cc41c8acfc1ee30b4868559058db97fa44b0137\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9744d2bf19762703704ecba885b7ac282c02eacf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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