CVE-2023-53809
Estado: AplazadaSin puntuar—
In the Linux kernel, the following vulnerability has been resolved:
l2tp: Avoid possible recursive deadlock in l2tp_tunnel_register()
When a file descriptor of pppol2tp socket is passed as file descriptor of UDP socket, a recursive deadlock occurs in l2tp_tunnel_register(). This situation is reproduced by the following program:
This program causes the following lockdep warning:
============================================ WARNING: possible recursive locking detected 6.2.0-rc5-00205-gc96618275234 #56 Not tainted -------------------------------------------- repro/8607 is trying to acquire lock: ffff8880213c8130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: l2tp_tunnel_register+0x2b7/0x11c0
Leer descripción completaMostrar menos
This patch fixes the issue by getting/creating the tunnel before locking the pppol2tp socket.
Detalles técnicos trazas, registros y código del informe original
int main(void)
{
int sock;
struct sockaddr_pppol2tp addr;
sock = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP);
if (sock < 0) {
perror("socket");
return 1;
}
addr.sa_family = AF_PPPOX;
addr.sa_protocol = PX_PROTO_OL2TP;
addr.pppol2tp.pid = 0;
addr.pppol2tp.fd = sock;
addr.pppol2tp.addr.sin_family = PF_INET;
addr.pppol2tp.addr.sin_port = htons(0);
addr.pppol2tp.addr.sin_addr.s_addr = inet_addr("192.168.0.1");
addr.pppol2tp.s_tunnel = 1;
addr.pppol2tp.s_session = 0;
addr.pppol2tp.d_tunnel = 0;
addr.pppol2tp.d_session = 0;
if (connect(sock, (const struct sockaddr *)&addr, sizeof(addr)) < 0) {
perror("connect");
return 1;
}
return 0;
}
but task is already holding lock:
ffff8880213c8130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppol2tp_connect+0xa82/0x1a30
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(sk_lock-AF_PPPOX);
lock(sk_lock-AF_PPPOX);
*** DEADLOCK ***
May be due to missing lock nesting notation
1 lock held by repro/8607:
#0: ffff8880213c8130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppol2tp_connect+0xa82/0x1a30
stack backtrace:
CPU: 0 PID: 8607 Comm: repro Not tainted 6.2.0-rc5-00205-gc96618275234 #56
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x100/0x178
__lock_acquire.cold+0x119/0x3b9
? lockdep_hardirqs_on_prepare+0x410/0x410
lock_acquire+0x1e0/0x610
? l2tp_tunnel_register+0x2b7/0x11c0
? lock_downgrade+0x710/0x710
? __fget_files+0x283/0x3e0
lock_sock_nested+0x3a/0xf0
? l2tp_tunnel_register+0x2b7/0x11c0
l2tp_tunnel_register+0x2b7/0x11c0
? sprintf+0xc4/0x100
? l2tp_tunnel_del_work+0x6b0/0x6b0
? debug_object_deactivate+0x320/0x320
? lockdep_init_map_type+0x16d/0x7a0
? lockdep_init_map_type+0x16d/0x7a0
? l2tp_tunnel_create+0x2bf/0x4b0
? l2tp_tunnel_create+0x3c6/0x4b0
pppol2tp_connect+0x14e1/0x1a30
? pppol2tp_put_sk+0xd0/0xd0
? aa_sk_perm+0x2b7/0xa80
? aa_af_perm+0x260/0x260
? bpf_lsm_socket_connect+0x9/0x10
? pppol2tp_put_sk+0xd0/0xd0
__sys_connect_file+0x14f/0x190
__sys_connect+0x133/0x160
? __sys_connect_file+0x190/0x190
? lockdep_hardirqs_on+0x7d/0x100
? ktime_get_coarse_real_ts64+0x1b7/0x200
? ktime_get_coarse_real_ts64+0x147/0x200
? __audit_syscall_entry+0x396/0x500
__x64_sys_connect+0x72/0xb0
do_syscall_64+0x38/0xb0
entry_SYSCALL_64_after_hwframe+0x63/0xcdCVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.19%
- Percentil entre todas las CVEs puntuadas: 7
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/4a413d360959962995e16a899cf2b9ef53e9fcb9
- https://git.kernel.org/stable/c/4bb736b40475528ac1aa8c98b368563618488a70
- https://git.kernel.org/stable/c/5370647dd745bb3d8f37057006be207ddd8e9314
- https://git.kernel.org/stable/c/9ca5e7ecab064f1f47da07f7c1ddf40e4bc0e5ac
- https://git.kernel.org/stable/c/f6df58aa15f7d469f69b1dd21b001ff483255244
JSON original (NVD)
Mostrar
{
"id": "CVE-2023-53809",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2d77e5c0ad79004b5ef901895437e9cce6dfcc7e",
"lessThan": "4a413d360959962995e16a899cf2b9ef53e9fcb9",
"versionType": "git"
},
{
"status": "affected",
"version": "77e8ed776cdb1a24b2aab8fe7c6f1f154235e1ce",
"lessThan": "f6df58aa15f7d469f69b1dd21b001ff483255244",
"versionType": "git"
},
{
"status": "affected",
"version": "cef0845b6dcfa2f6c2c832e7f9622551456c741d",
"lessThan": "4bb736b40475528ac1aa8c98b368563618488a70",
"versionType": "git"
},
{
"status": "affected",
"version": "0b2c59720e65885a394a017d0cf9cab118914682",
"lessThan": "5370647dd745bb3d8f37057006be207ddd8e9314",
"versionType": "git"
},
{
"status": "affected",
"version": "0b2c59720e65885a394a017d0cf9cab118914682",
"lessThan": "9ca5e7ecab064f1f47da07f7c1ddf40e4bc0e5ac",
"versionType": "git"
},
{
"status": "affected",
"version": "5.10.166",
"lessThan": "5.10.173",
"versionType": "semver"
},
{
"status": "affected",
"version": "5.15.91",
"lessThan": "5.15.99",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.1.9",
"lessThan": "6.1.16",
"versionType": "semver"
}
],
"programFiles": [
"net/l2tp/l2tp_ppp.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.2"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.2",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.173",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.99",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.16",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.2.3",
"versionType": "semver",
"lessThanOrEqual": "6.2.*"
},
{
"status": "unaffected",
"version": "6.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/l2tp/l2tp_ppp.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2025-12-09T01:16:52.940",
"references": [
{
"url": "https://git.kernel.org/stable/c/4a413d360959962995e16a899cf2b9ef53e9fcb9",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/4bb736b40475528ac1aa8c98b368563618488a70",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/5370647dd745bb3d8f37057006be207ddd8e9314",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9ca5e7ecab064f1f47da07f7c1ddf40e4bc0e5ac",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/f6df58aa15f7d469f69b1dd21b001ff483255244",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Deferred",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nl2tp: Avoid possible recursive deadlock in l2tp_tunnel_register()\n\nWhen a file descriptor of pppol2tp socket is passed as file descriptor\nof UDP socket, a recursive deadlock occurs in l2tp_tunnel_register().\nThis situation is reproduced by the following program:\n\nint main(void)\n{\n\tint sock;\n\tstruct sockaddr_pppol2tp addr;\n\n\tsock = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP);\n\tif (sock < 0) {\n\t\tperror(\"socket\");\n\t\treturn 1;\n\t}\n\n\taddr.sa_family = AF_PPPOX;\n\taddr.sa_protocol = PX_PROTO_OL2TP;\n\taddr.pppol2tp.pid = 0;\n\taddr.pppol2tp.fd = sock;\n\taddr.pppol2tp.addr.sin_family = PF_INET;\n\taddr.pppol2tp.addr.sin_port = htons(0);\n\taddr.pppol2tp.addr.sin_addr.s_addr = inet_addr(\"192.168.0.1\");\n\taddr.pppol2tp.s_tunnel = 1;\n\taddr.pppol2tp.s_session = 0;\n\taddr.pppol2tp.d_tunnel = 0;\n\taddr.pppol2tp.d_session = 0;\n\n\tif (connect(sock, (const struct sockaddr *)&addr, sizeof(addr)) < 0) {\n\t\tperror(\"connect\");\n\t\treturn 1;\n\t}\n\n\treturn 0;\n}\n\nThis program causes the following lockdep warning:\n\n ============================================\n WARNING: possible recursive locking detected\n 6.2.0-rc5-00205-gc96618275234 #56 Not tainted\n --------------------------------------------\n repro/8607 is trying to acquire lock:\n ffff8880213c8130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: l2tp_tunnel_register+0x2b7/0x11c0\n\n but task is already holding lock:\n ffff8880213c8130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppol2tp_connect+0xa82/0x1a30\n\n other info that might help us debug this:\n Possible unsafe locking scenario:\n\n CPU0\n ----\n lock(sk_lock-AF_PPPOX);\n lock(sk_lock-AF_PPPOX);\n\n *** DEADLOCK ***\n\n May be due to missing lock nesting notation\n\n 1 lock held by repro/8607:\n #0: ffff8880213c8130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppol2tp_connect+0xa82/0x1a30\n\n stack backtrace:\n CPU: 0 PID: 8607 Comm: repro Not tainted 6.2.0-rc5-00205-gc96618275234 #56\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014\n Call Trace:\n <TASK>\n dump_stack_lvl+0x100/0x178\n __lock_acquire.cold+0x119/0x3b9\n ? lockdep_hardirqs_on_prepare+0x410/0x410\n lock_acquire+0x1e0/0x610\n ? l2tp_tunnel_register+0x2b7/0x11c0\n ? lock_downgrade+0x710/0x710\n ? __fget_files+0x283/0x3e0\n lock_sock_nested+0x3a/0xf0\n ? l2tp_tunnel_register+0x2b7/0x11c0\n l2tp_tunnel_register+0x2b7/0x11c0\n ? sprintf+0xc4/0x100\n ? l2tp_tunnel_del_work+0x6b0/0x6b0\n ? debug_object_deactivate+0x320/0x320\n ? lockdep_init_map_type+0x16d/0x7a0\n ? lockdep_init_map_type+0x16d/0x7a0\n ? l2tp_tunnel_create+0x2bf/0x4b0\n ? l2tp_tunnel_create+0x3c6/0x4b0\n pppol2tp_connect+0x14e1/0x1a30\n ? pppol2tp_put_sk+0xd0/0xd0\n ? aa_sk_perm+0x2b7/0xa80\n ? aa_af_perm+0x260/0x260\n ? bpf_lsm_socket_connect+0x9/0x10\n ? pppol2tp_put_sk+0xd0/0xd0\n __sys_connect_file+0x14f/0x190\n __sys_connect+0x133/0x160\n ? __sys_connect_file+0x190/0x190\n ? lockdep_hardirqs_on+0x7d/0x100\n ? ktime_get_coarse_real_ts64+0x1b7/0x200\n ? ktime_get_coarse_real_ts64+0x147/0x200\n ? __audit_syscall_entry+0x396/0x500\n __x64_sys_connect+0x72/0xb0\n do_syscall_64+0x38/0xb0\n entry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nThis patch fixes the issue by getting/creating the tunnel before\nlocking the pppol2tp socket."
}
],
"lastModified": "2026-06-17T06:46:06.580",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}