CVE-2024-35969

ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr

Severity Score

5.5

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Track

*SSVC

Descriptions

In the Linux kernel, the following vulnerability has been resolved:

ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr

Although ipv6_get_ifaddr walks inet6_addr_lst under the RCU lock, it
still means hlist_for_each_entry_rcu can return an item that got removed
from the list. The memory itself of such item is not freed thanks to RCU
but nothing guarantees the actual content of the memory is sane.

In particular, the reference count can be zero. This can happen if
ipv6_del_addr is called in parallel. ipv6_del_addr removes the entry
from inet6_addr_lst (hlist_del_init_rcu(&ifp->addr_lst)) and drops all
references (__in6_ifa_put(ifp) + in6_ifa_put(ifp)). With bad enough
timing, this can happen:

1. In ipv6_get_ifaddr, hlist_for_each_entry_rcu returns an entry.

2. Then, the whole ipv6_del_addr is executed for the given entry. The
reference count drops to zero and kfree_rcu is scheduled.

3. ipv6_get_ifaddr continues and tries to increments the reference count
(in6_ifa_hold).

4. The rcu is unlocked and the entry is freed.

5. The freed entry is returned.

Prevent increasing of the reference count in such case. The name
in6_ifa_hold_safe is chosen to mimic the existing fib6_info_hold_safe.

[ 41.506330] refcount_t: addition on 0; use-after-free.
[ 41.506760] WARNING: CPU: 0 PID: 595 at lib/refcount.c:25 refcount_warn_saturate+0xa5/0x130
[ 41.507413] Modules linked in: veth bridge stp llc
[ 41.507821] CPU: 0 PID: 595 Comm: python3 Not tainted 6.9.0-rc2.main-00208-g49563be82afa #14
[ 41.508479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
[ 41.509163] RIP: 0010:refcount_warn_saturate+0xa5/0x130
[ 41.509586] Code: ad ff 90 0f 0b 90 90 c3 cc cc cc cc 80 3d c0 30 ad 01 00 75 a0 c6 05 b7 30 ad 01 01 90 48 c7 c7 38 cc 7a 8c e8 cc 18 ad ff 90 <0f> 0b 90 90 c3 cc cc cc cc 80 3d 98 30 ad 01 00 0f 85 75 ff ff ff
[ 41.510956] RSP: 0018:ffffbda3c026baf0 EFLAGS: 00010282
[ 41.511368] RAX: 0000000000000000 RBX: ffff9e9c46914800 RCX: 0000000000000000
[ 41.511910] RDX: ffff9e9c7ec29c00 RSI: ffff9e9c7ec1c900 RDI: ffff9e9c7ec1c900
[ 41.512445] RBP: ffff9e9c43660c9c R08: 0000000000009ffb R09: 00000000ffffdfff
[ 41.512998] R10: 00000000ffffdfff R11: ffffffff8ca58a40 R12: ffff9e9c4339a000
[ 41.513534] R13: 0000000000000001 R14: ffff9e9c438a0000 R15: ffffbda3c026bb48
[ 41.514086] FS: 00007fbc4cda1740(0000) GS:ffff9e9c7ec00000(0000) knlGS:0000000000000000
[ 41.514726] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 41.515176] CR2: 000056233b337d88 CR3: 000000000376e006 CR4: 0000000000370ef0
[ 41.515713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 41.516252] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 41.516799] Call Trace:
[ 41.517037] <TASK>
[ 41.517249] ? __warn+0x7b/0x120
[ 41.517535] ? refcount_warn_saturate+0xa5/0x130
[ 41.517923] ? report_bug+0x164/0x190
[ 41.518240] ? handle_bug+0x3d/0x70
[ 41.518541] ? exc_invalid_op+0x17/0x70
[ 41.520972] ? asm_exc_invalid_op+0x1a/0x20
[ 41.521325] ? refcount_warn_saturate+0xa5/0x130
[ 41.521708] ipv6_get_ifaddr+0xda/0xe0
[ 41.522035] inet6_rtm_getaddr+0x342/0x3f0
[ 41.522376] ? __pfx_inet6_rtm_getaddr+0x10/0x10
[ 41.522758] rtnetlink_rcv_msg+0x334/0x3d0
[ 41.523102] ? netlink_unicast+0x30f/0x390
[ 41.523445] ? __pfx_rtnetlink_rcv_msg+0x10/0x10
[ 41.523832] netlink_rcv_skb+0x53/0x100
[ 41.524157] netlink_unicast+0x23b/0x390
[ 41.524484] netlink_sendmsg+0x1f2/0x440
[ 41.524826] __sys_sendto+0x1d8/0x1f0
[ 41.525145] __x64_sys_sendto+0x1f/0x30
[ 41.525467] do_syscall_64+0xa5/0x1b0
[ 41.525794] entry_SYSCALL_64_after_hwframe+0x72/0x7a
[ 41.526213] RIP: 0033:0x7fbc4cfcea9a
[ 41.526528] Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89
[ 41.527942] RSP: 002b:00007f
---truncated---

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: ipv6: corrige la condición de ejecución entre ipv6_get_ifaddr e ipv6_del_addr .Aunque ipv6_get_ifaddr recorre inet6_addr_lst bajo el bloqueo de RCU, todavía significa que hlist_for_each_entry_rcu puede devolver un elemento que se eliminó de la lista. La memoria en sí de dicho elemento no se libera gracias a RCU, pero nada garantiza que el contenido real de la memoria sea sano. En particular, el recuento de referencia puede ser cero. Esto puede suceder si se llama a ipv6_del_addr en paralelo. ipv6_del_addr elimina la entrada de inet6_addr_lst (hlist_del_init_rcu(&ifp->addr_lst)) y elimina todas las referencias (__in6_ifa_put(ifp) + in6_ifa_put(ifp)). En un momento bastante malo, esto puede suceder: 1. En ipv6_get_ifaddr, hlist_for_each_entry_rcu devuelve una entrada. 2. Luego, se ejecuta todo el ipv6_del_addr para la entrada dada. El recuento de referencias cae a cero y se programa kfree_rcu. 3. ipv6_get_ifaddr continúa e intenta incrementar el recuento de referencias (in6_ifa_hold). 4. Se desbloquea la rcu y se libera la entrada. 5. Se devuelve la entrada liberada. Evite el aumento del recuento de referencia en tal caso. El nombre in6_ifa_hold_safe se elige para imitar el fib6_info_hold_safe existente. [41.506330] refcount_t: suma en 0; uso después de la liberación. [ 41.506760] ADVERTENCIA: CPU: 0 PID: 595 en lib/refcount.c:25 refcount_warn_saturate+0xa5/0x130 [ 41.507413] Módulos vinculados en: veth bridge stp llc [ 41.507821] CPU: 0 PID: 595 Comm: python3 No contaminado 6.9 .0-rc2.main-00208-g49563be82afa #14 [ 41.508479] Nombre del hardware: PC estándar QEMU (i440FX + PIIX, 1996) [ 41.509163] RIP: 0010:refcount_warn_saturate+0xa5/0x130 [ 41.509586] Código: ad ff 90 0f 0b 90 90 c3 cc cc cc 80 3d c0 30 ad 01 00 75 a0 c6 05 b7 30 ad 01 01 90 48 c7 c7 38 cc 7a 8c e8 cc 18 ad ff 90 <0f> 0b 90 90 c3 cc cc cc 80 3d 98 30 ad 01 00 0f 85 75 ff ff ff [ 41.510956] RSP: 0018:ffffbda3c026baf0 EFLAGS: 00010282 [ 41.511368] RAX: 0000000000000000 RBX: 800 RCX: 0000000000000000 [ 41.511910] RDX: ffff9e9c7ec29c00 RSI: ffff9e9c7ec1c900 RDI: ffff9e9c7ec1c900 [ 41.512445] RBP : ffff9e9c43660c9c R08: 0000000000009ffb R09: 00000000ffffdfff [ 41.512998] R10: 00000000ffffdfff R11: fffffff8ca58a40 R12: ffff9e9c4339a000 [ 41 .513534] R13: 0000000000000001 R14: ffff9e9c438a0000 R15: ffffbda3c026bb48 [ 41.514086] FS: 00007fbc4cda1740(0000) GS:ffff9e9c7ec00000(0000) lGS:0000000000000000 [ 41.514726] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 41.515176] CR2: 000056233b337d88 CR3: 000000000376e006 CR4: 0000000000370ef 0 [ 41.515713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 41.516252] DR3: 00000000000000000 DR6: 00000000ffe0ff0 DR7 : 0000000000000400 [ 41.516799] Seguimiento de llamadas: [ 41.517037] [ 41.517249] ? __warn+0x7b/0x120 [ 41.517535] ? refcount_warn_saturate+0xa5/0x130 [41.517923]? report_bug+0x164/0x190 [41.518240]? handle_bug+0x3d/0x70 [41.518541]? exc_invalid_op+0x17/0x70 [41.520972]? asm_exc_invalid_op+0x1a/0x20 [41.521325]? refcount_warn_saturate+0xa5/0x130 [ 41.521708] ipv6_get_ifaddr+0xda/0xe0 [ 41.522035] inet6_rtm_getaddr+0x342/0x3f0 [ 41.522376] ? __pfx_inet6_rtm_getaddr+0x10/0x10 [ 41.522758] rtnetlink_rcv_msg+0x334/0x3d0 [ 41.523102] ? netlink_unicast+0x30f/0x390 [41.523445]? __pfx_rtnetlink_rcv_msg+0x10/0x10 [ 41.523832] netlink_rcv_skb+0x53/0x100 [ 41.524157] netlink_unicast+0x23b/0x390 [ 41.524484] netlink_sendmsg+0x1f2/0x440 [ 41. 524826] __sys_sendto+0x1d8/0x1f0 [ 41.525145] __x64_sys_sendto+0x1f/0x30 [ 41.525467] do_syscall_64+ 0xa5/0x1b0 [41.525794] Entry_SYSCALL_64_after_hwframe+0x72/0x7a [41.526213] RIP: 0033:0x7fbc4cfcea9a [41.526528] Código: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89 [ 41.527942] 002b:00007f-- -truncado---

*Credits: N/A

CVSS Scores

Red Hatv3.1 5.5

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

* Common Vulnerability Scoring System

SSVC

Decision:Track

Exploitation

None

Automatable

Tech. Impact

Partial

* Organization's Worst-case Scenario

Timeline

2024-05-17 CVE Reserved
2024-05-20 CVE Published
2024-05-21 EPSS Updated
2024-08-02 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (13)

URL	Tag	Source
https://git.kernel.org/stable/c/5c578aedcb21d79eeb4e9cf04ca5b276ac82614c	Vuln. Introduced
https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html
https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/b4b3b69a19016d4e7fbdbd1dbcc184915eb862e1	2024-05-02
https://git.kernel.org/stable/c/cca606e14264098cba65efa82790825dbf69e903	2024-05-02
https://git.kernel.org/stable/c/3fb02ec57ead2891a2306af8c51a306bc5945e70	2024-05-02
https://git.kernel.org/stable/c/4b19e9507c275de0cfe61c24db69179dc52cf9fb	2024-04-17
https://git.kernel.org/stable/c/de76ae9ea1a6cf9e77fcec4f2df2904e26c23ceb	2024-04-17
https://git.kernel.org/stable/c/01b11a0566670612bd464a932e5ac2eae53d8652	2024-04-17
https://git.kernel.org/stable/c/6cdb20c342cd0193d3e956e3d83981d0f438bb83	2024-04-17
https://git.kernel.org/stable/c/7633c4da919ad51164acbf1aa322cc1a3ead6129	2024-04-10

URL	Date	SRC
https://access.redhat.com/security/cve/CVE-2024-35969	2024-08-15
https://bugzilla.redhat.com/show_bug.cgi?id=2281900	2024-08-15

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.35 < 4.19.313 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.35 < 4.19.313"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.35 < 5.4.275 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.35 < 5.4.275"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.35 < 5.10.216 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.35 < 5.10.216"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.35 < 5.15.156 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.35 < 5.15.156"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.35 < 6.1.87 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.35 < 6.1.87"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.35 < 6.6.28 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.35 < 6.6.28"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.35 < 6.8.7 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.35 < 6.8.7"		en		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 2.6.35 < 6.9 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.35 < 6.9"		en		Affected