// For flags

CVE-2022-48721

net/smc: Forward wakeup to smc socket waitqueue after fallback

Severity Score

"-"
*CVSS v-

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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

net/smc: Forward wakeup to smc socket waitqueue after fallback

When we replace TCP with SMC and a fallback occurs, there may be
some socket waitqueue entries remaining in smc socket->wq, such
as eppoll_entries inserted by userspace applications.

After the fallback, data flows over TCP/IP and only clcsocket->wq
will be woken up. Applications can't be notified by the entries
which were inserted in smc socket->wq before fallback. So we need
a mechanism to wake up smc socket->wq at the same time if some
entries remaining in it.

The current workaround is to transfer the entries from smc socket->wq
to clcsock->wq during the fallback. But this may cause a crash
like this:

general protection fault, probably for non-canonical address 0xdead000000000100: 0000 [#1] PREEMPT SMP PTI
CPU: 3 PID: 0 Comm: swapper/3 Kdump: loaded Tainted: G E 5.16.0+ #107
RIP: 0010:__wake_up_common+0x65/0x170
Call Trace:
<IRQ>
__wake_up_common_lock+0x7a/0xc0
sock_def_readable+0x3c/0x70
tcp_data_queue+0x4a7/0xc40
tcp_rcv_established+0x32f/0x660
? sk_filter_trim_cap+0xcb/0x2e0
tcp_v4_do_rcv+0x10b/0x260
tcp_v4_rcv+0xd2a/0xde0
ip_protocol_deliver_rcu+0x3b/0x1d0
ip_local_deliver_finish+0x54/0x60
ip_local_deliver+0x6a/0x110
? tcp_v4_early_demux+0xa2/0x140
? tcp_v4_early_demux+0x10d/0x140
ip_sublist_rcv_finish+0x49/0x60
ip_sublist_rcv+0x19d/0x230
ip_list_rcv+0x13e/0x170
__netif_receive_skb_list_core+0x1c2/0x240
netif_receive_skb_list_internal+0x1e6/0x320
napi_complete_done+0x11d/0x190
mlx5e_napi_poll+0x163/0x6b0 [mlx5_core]
__napi_poll+0x3c/0x1b0
net_rx_action+0x27c/0x300
__do_softirq+0x114/0x2d2
irq_exit_rcu+0xb4/0xe0
common_interrupt+0xba/0xe0
</IRQ>
<TASK>

The crash is caused by privately transferring waitqueue entries from
smc socket->wq to clcsock->wq. The owners of these entries, such as
epoll, have no idea that the entries have been transferred to a
different socket wait queue and still use original waitqueue spinlock
(smc socket->wq.wait.lock) to make the entries operation exclusive,
but it doesn't work. The operations to the entries, such as removing
from the waitqueue (now is clcsock->wq after fallback), may cause a
crash when clcsock waitqueue is being iterated over at the moment.

This patch tries to fix this by no longer transferring wait queue
entries privately, but introducing own implementations of clcsock's
callback functions in fallback situation. The callback functions will
forward the wakeup to smc socket->wq if clcsock->wq is actually woken
up and smc socket->wq has remaining entries.

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: net/smc: Reenviar activación a la cola de espera del socket smc después del respaldo Cuando reemplazamos TCP con SMC y se produce un respaldo, es posible que queden algunas entradas de la cola de espera del socket en el socket smc-&gt;wq. como eppoll_entries insertados por aplicaciones de espacio de usuario. Después del respaldo, los datos fluyen a través de TCP/IP y solo se activará clcsocket-&gt;wq. Las aplicaciones no pueden ser notificadas por las entradas que se insertaron en smc socket-&gt;wq antes del respaldo. Entonces necesitamos un mecanismo para activar smc socket-&gt;wq al mismo tiempo si quedan algunas entradas en él. La solución actual es transferir las entradas de smc socket-&gt;wq a clcsock-&gt;wq durante el respaldo. Pero esto puede causar un fallo como este: fallo de protección general, probablemente para la dirección no canónica 0xdead000000000100: 0000 [#1] PREEMPT SMP PTI CPU: 3 PID: 0 Comm: swapper/3 Kdump: cargado Contaminado: GE 5.16.0+ #107 RIP: 0010:__wake_up_common+0x65/0x170 Seguimiento de llamadas: __wake_up_common_lock+0x7a/0xc0 sock_def_readable+0x3c/0x70 tcp_data_queue+0x4a7/0xc40 tcp_rcv_establecido+0x32f/0x660 ? sk_filter_trim_cap+0xcb/0x2e0 tcp_v4_do_rcv+0x10b/0x260 tcp_v4_rcv+0xd2a/0xde0 ip_protocol_deliver_rcu+0x3b/0x1d0 ip_local_deliver_finish+0x54/0x60 0 ? tcp_v4_early_demux+0xa2/0x140? tcp_v4_early_demux+0x10d/0x140 ip_sublist_rcv_finish+0x49/0x60 ip_sublist_rcv+0x19d/0x230 ip_list_rcv+0x13e/0x170 __netif_receive_skb_list_core+0x1c2/0x240 netif_receive_skb_list_ interno+0x1e6/0x320 napi_complete_done+0x11d/0x190 mlx5e_napi_poll+0x163/0x6b0 [mlx5_core] __napi_poll+0x3c/0x1b0 net_rx_action+ 0x27c/0x300 __do_softirq+0x114/0x2d2 irq_exit_rcu+0xb4/0xe0 common_interrupt+0xba/0xe0 El bloqueo se debe a la transferencia privada de entradas de la cola de espera desde smc socket-&gt;wq a clcsock-&gt;wq. Los propietarios de estas entradas, como epoll, no tienen idea de que las entradas se han transferido a una cola de espera de socket diferente y aún usan el spinlock de cola de espera original (smc socket-&gt;wq.wait.lock) para que la operación de entradas sea exclusiva, pero no funciona. Las operaciones realizadas en las entradas, como la eliminación de la cola de espera (ahora es clcsock-&gt;wq después del respaldo), pueden causar un bloqueo cuando se está iterando sobre la cola de espera de clcsock en este momento. Este parche intenta solucionar este problema al no transferir las entradas de la cola de espera de forma privada, sino al introducir implementaciones propias de las funciones de devolución de llamada de clcsock en situaciones de reserva. Las funciones de devolución de llamada reenviarán la activación a smc socket-&gt;wq si clcsock-&gt;wq realmente se activa y smc socket-&gt;wq tiene entradas restantes.

*Credits: N/A
CVSS Scores
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* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-06-20 CVE Reserved
  • 2024-06-20 CVE Published
  • 2024-06-21 EPSS Updated
  • 2024-12-19 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
CAPEC
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"
>= 5.15.7 < 5.15.22
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.15.7 < 5.15.22"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.16 < 5.16.8
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.16 < 5.16.8"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.16 < 5.17
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.16 < 5.17"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
5.4.164
Search vendor "Linux" for product "Linux Kernel" and version "5.4.164"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
5.10.84
Search vendor "Linux" for product "Linux Kernel" and version "5.10.84"
en
Affected