Описание
In the Linux kernel, the following vulnerability has been resolved:
smc: Fix various oops due to inet_sock type confusion.
syzbot reported weird splats [0][1] in cipso_v4_sock_setattr() while
freeing inet_sk(sk)->inet_opt.
The address was freed multiple times even though it was read-only memory.
cipso_v4_sock_setattr() did nothing wrong, and the root cause was type
confusion.
The cited commit made it possible to create smc_sock as an INET socket.
The issue is that struct smc_sock does not have struct inet_sock as the
first member but hijacks AF_INET and AF_INET6 sk_family, which confuses
various places.
In this case, inet_sock.inet_opt was actually smc_sock.clcsk_data_ready(),
which is an address of a function in the text segment.
$ pahole -C inet_sock vmlinux
struct inet_sock {
...
struct ip_options_rcu * inet_opt; /* 784 8 */
$ pahole -C smc_sock vmlinux
struct smc_sock {
...
void (*clcsk_data_ready)(struct sock ); / 784 8 */
The same issue for another field was reported before. [2][3]
At that time, an ugly hack was suggested [4], but it makes both INET
and SMC code error-prone and hard to change.
Also, yet another variant was fixed by a hacky commit 98d4435efcbf3
("net/smc: prevent NULL pointer dereference in txopt_get").
Instead of papering over the root cause by such hacks, we should not
allow non-INET socket to reuse the INET infra.
Let's add inet_sock as the first member of smc_sock.
[0]:
kvfree_call_rcu(): Double-freed call. rcu_head 000000006921da73
WARNING: CPU: 0 PID: 6718 at mm/slab_common.c:1956 kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955
Modules linked in:
CPU: 0 UID: 0 PID: 6718 Comm: syz.0.17 Tainted: G W 6.16.0-rc4-syzkaller-g7482bb149b9f #0 PREEMPT
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955
lr : kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955
sp : ffff8000a03a7730
x29: ffff8000a03a7730 x28: 00000000fffffff5 x27: 1fffe000184823d3
x26: dfff800000000000 x25: ffff0000c2411e9e x24: ffff0000dd88da00
x23: ffff8000891ac9a0 x22: 00000000ffffffea x21: ffff8000891ac9a0
x20: ffff8000891ac9a0 x19: ffff80008afc2480 x18: 00000000ffffffff
x17: 0000000000000000 x16: ffff80008ae642c8 x15: ffff700011ede14c
x14: 1ffff00011ede14c x13: 0000000000000004 x12: ffffffffffffffff
x11: ffff700011ede14c x10: 0000000000ff0100 x9 : 5fa3c1ffaf0ff000
x8 : 5fa3c1ffaf0ff000 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000a03a7078 x4 : ffff80008f766c20 x3 : ffff80008054d360
x2 : 0000000000000000 x1 : 0000000000000201 x0 : 0000000000000000
Call trace:
kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955 (P)
cipso_v4_sock_setattr+0x2f0/0x3f4 net/ipv4/cipso_ipv4.c:1914
netlbl_sock_setattr+0x240/0x334 net/netlabel/netlabel_kapi.c:1000
smack_netlbl_add+0xa8/0x158 security/smack/smack_lsm.c:2581
smack_inode_setsecurity+0x378/0x430 security/smack/smack_lsm.c:2912
security_inode_setsecurity+0x118/0x3c0 security/security.c:2706
__vfs_setxattr_noperm+0x174/0x5c4 fs/xattr.c:251
__vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:295
vfs_setxattr+0x158/0x2ac fs/xattr.c:321
do_setxattr fs/xattr.c:636 [inline]
file_setxattr+0x1b8/0x294 fs/xattr.c:646
path_setxattrat+0x2ac/0x320 fs/xattr.c:711
__do_sys_fsetxattr fs/xattr.c:761 [inline]
__se_sys_fsetxattr fs/xattr.c:758 [inline]
__arm64_sys_fsetxattr+0xc0/0xdc fs/xattr.c:758
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879
el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
[
---truncated---
A flaw was found in the Linux kernel. This vulnerability exists within the smc (Shared Memory Communications over Remote Direct Memory Access) socket type implementation, where a type confusion error can occur. A local user can exploit this flaw, leading to a double-free condition that results in a Denial of Service (DoS) on the system.
Отчет
A denial-of-service vulnerability of moderate impact was found in the Linux kernel SMC (Shared Memory Communications over RDMA) socket implementation in Red Hat Enterprise Linux 9 and 10. The SMC socket structure (struct smc_sock) reuses the AF_INET/AF_INET6 socket family without embedding struct inet_sock as its first member, so INET-specific code misinterprets SMC socket fields: in the CIPSO/NetLabel path used by SMACK labeling, the inet_sock.inet_opt pointer actually aliases the smc_sock.clcsk_data_ready function pointer in read-only kernel text. A local user with typical privileges on the system can exploit this type confusion by creating an SMC socket that is handled as an INET socket and triggering INET socket-option processing, causing the kernel to attempt to free read-only kernel memory multiple times (a double-free) and leading to a kernel oops that crashes the system. Red Hat Enterprise Linux 9 and 10 (kernel and kernel-rt) are affected and are currently recorded with an out-of-support-scope resolution. Red Hat Enterprise Linux 6, 7, and 8 (kernel and kernel-rt) and Red Hat In-Vehicle OS 1 are not affected because the vulnerable code is not present in those offerings. Red Hat rates this flaw Moderate (CVSS 3.1 score 5.5, AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) because a successful attack affects only system availability; the CVE.org record scores it High (7.8) by assuming full confidentiality, integrity, and availability impact, which is not supported by the technical evidence.
Меры по смягчению последствий
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Out of support scope |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: smc: Fix various oops due to inet_sock type confusion. syzbot reported weird splats [0][1] in cipso_v4_sock_setattr() while freeing inet_sk(sk)->inet_opt. The address was freed multiple times even though it was read-only memory. cipso_v4_sock_setattr() did nothing wrong, and the root cause was type confusion. The cited commit made it possible to create smc_sock as an INET socket. The issue is that struct smc_sock does not have struct inet_sock as the first member but hijacks AF_INET and AF_INET6 sk_family, which confuses various places. In this case, inet_sock.inet_opt was actually smc_sock.clcsk_data_ready(), which is an address of a function in the text segment. $ pahole -C inet_sock vmlinux struct inet_sock { ... struct ip_options_rcu * inet_opt; /* 784 8 */ $ pahole -C smc_sock vmlinux struct smc_sock { ... void (*clcsk_data_ready)(struct sock *); /* 784 8 */ The sa...
In the Linux kernel, the following vulnerability has been resolved: smc: Fix various oops due to inet_sock type confusion. syzbot reported weird splats [0][1] in cipso_v4_sock_setattr() while freeing inet_sk(sk)->inet_opt. The address was freed multiple times even though it was read-only memory. cipso_v4_sock_setattr() did nothing wrong, and the root cause was type confusion. The cited commit made it possible to create smc_sock as an INET socket. The issue is that struct smc_sock does not have struct inet_sock as the first member but hijacks AF_INET and AF_INET6 sk_family, which confuses various places. In this case, inet_sock.inet_opt was actually smc_sock.clcsk_data_ready(), which is an address of a function in the text segment. $ pahole -C inet_sock vmlinux struct inet_sock { ... struct ip_options_rcu * inet_opt; /* 784 8 */ $ pahole -C smc_sock vmlinux struct smc_sock { ... void (*clcsk_data_ready)(
In the Linux kernel, the following vulnerability has been resolved: s ...
In the Linux kernel, the following vulnerability has been resolved: smc: Fix various oops due to inet_sock type confusion. syzbot reported weird splats [0][1] in cipso_v4_sock_setattr() while freeing inet_sk(sk)->inet_opt. The address was freed multiple times even though it was read-only memory. cipso_v4_sock_setattr() did nothing wrong, and the root cause was type confusion. The cited commit made it possible to create smc_sock as an INET socket. The issue is that struct smc_sock does not have struct inet_sock as the first member but hijacks AF_INET and AF_INET6 sk_family, which confuses various places. In this case, inet_sock.inet_opt was actually smc_sock.clcsk_data_ready(), which is an address of a function in the text segment. $ pahole -C inet_sock vmlinux struct inet_sock { ... struct ip_options_rcu * inet_opt; /* 784 8 */ $ pahole -C smc_sock vmlinux struct smc_sock { ... void (*clcsk_data_read...
Уязвимость функции cipso_v4_sock_setattr() компонента smc ядра операционной системы Linux, позволяющая нарушителю вызвать отказ в обслуживании
EPSS
5.5 Medium
CVSS3