CVE-2022-49201
Estado: ModificadaMedia (4.7)—
In the Linux kernel, the following vulnerability has been resolved:
ibmvnic: fix race between xmit and reset
There is a race between reset and the transmit paths that can lead to ibmvnic_xmit() accessing an scrq after it has been freed in the reset path. It can result in a crash like:
The immediate cause of the crash is the access of tx_scrq in the following snippet during a reset, where the tx_scrq can be either NULL or an address that will soon be invalid:
But beyond that, the call to ibmvnic_xmit() itself is not safe during a reset and the reset path attempts to avoid this by stopping the queue in ibmvnic_cleanup(). However just after the queue was stopped, an in-flight ibmvnic_complete_tx() could have restarted the queue even as the reset is progressing.
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Since the queue was restarted we could get a call to ibmvnic_xmit() which can then access the bad tx_scrq (or other fields).
We cannot however simply have ibmvnic_complete_tx() check the ->resetting bit and skip starting the queue. This can race at the "back-end" of a good reset which just restarted the queue but has not cleared the ->resetting bit yet. If we skip restarting the queue due to ->resetting being true, the queue would remain stopped indefinitely potentially leading to transmit timeouts.
IOW ->resetting is too broad for this purpose. Instead use a new flag that indicates whether or not the queues are active. Only the open/ reset paths control when the queues are active. ibmvnic_complete_tx() and others wake up the queue only if the queue is marked active.
->resetting = true ->tx_queues_active = false disable tx queues ... ->tx_queues_active = true start tx queues
To ensure that ->tx_queues_active and state of the queues are consistent, we need a lock which:
Detalles técnicos trazas, registros y código del informe original
Kernel attempted to read user page (0) - exploit attempt? (uid: 0)
BUG: Kernel NULL pointer dereference on read at 0x00000000
Faulting instruction address: 0xc0080000016189f8
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP [c0080000016189f8] ibmvnic_xmit+0x60/0xb60 [ibmvnic]
LR [c000000000c0046c] dev_hard_start_xmit+0x11c/0x280
Call Trace:
[c008000001618f08] ibmvnic_xmit+0x570/0xb60 [ibmvnic] (unreliable)
[c000000000c0046c] dev_hard_start_xmit+0x11c/0x280
[c000000000c9cfcc] sch_direct_xmit+0xec/0x330
[c000000000bfe640] __dev_xmit_skb+0x3a0/0x9d0
[c000000000c00ad4] __dev_queue_xmit+0x394/0x730
[c008000002db813c] __bond_start_xmit+0x254/0x450 [bonding]
[c008000002db8378] bond_start_xmit+0x40/0xc0 [bonding]
[c000000000c0046c] dev_hard_start_xmit+0x11c/0x280
[c000000000c00ca4] __dev_queue_xmit+0x564/0x730
[c000000000cf97e0] neigh_hh_output+0xd0/0x180
[c000000000cfa69c] ip_finish_output2+0x31c/0x5c0
[c000000000cfd244] __ip_queue_xmit+0x194/0x4f0
[c000000000d2a3c4] __tcp_transmit_skb+0x434/0x9b0
[c000000000d2d1e0] __tcp_retransmit_skb+0x1d0/0x6a0
[c000000000d2d984] tcp_retransmit_skb+0x34/0x130
[c000000000d310e8] tcp_retransmit_timer+0x388/0x6d0
[c000000000d315ec] tcp_write_timer_handler+0x1bc/0x330
[c000000000d317bc] tcp_write_timer+0x5c/0x200
[c000000000243270] call_timer_fn+0x50/0x1c0
[c000000000243704] __run_timers.part.0+0x324/0x460
[c000000000243894] run_timer_softirq+0x54/0xa0
[c000000000ea713c] __do_softirq+0x15c/0x3e0
[c000000000166258] __irq_exit_rcu+0x158/0x190
[c000000000166420] irq_exit+0x20/0x40
[c00000000002853c] timer_interrupt+0x14c/0x2b0
[c000000000009a00] decrementer_common_virt+0x210/0x220
--- interrupt: 900 at plpar_hcall_norets_notrace+0x18/0x2c
ibmvnic_xmit()
{
...
tx_scrq = adapter->tx_scrq[queue_num];
txq = netdev_get_tx_queue(netdev, queue_num);
ind_bufp = &tx_scrq->ind_buf;
if (test_bit(0, &adapter->resetting)) {
...
}
So we will have:
A. reset/open thread in ibmvnic_cleanup() and __ibmvnic_open()
B. Tx interrupt in ibmvnic_complete_tx():
if (->tx_queues_active)
netif_wake_subqueue();
- must also be taken in the interrupt path (ibmvnic_complete_tx())
- shared across the multiple
---truncated---CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 4.7
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.50%
- Percentil entre todas las CVEs puntuadas: 40
- 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)
CWE
- CWE-362, CWE-476
- CWE-476
Referencias
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nibmvnic: fix race between xmit and reset\n\nThere is a race between reset and the transmit paths that can lead to\nibmvnic_xmit() accessing an scrq after it has been freed in the reset\npath. It can result in a crash like:\n\n\tKernel attempted to read user page (0) - exploit attempt? (uid: 0)\n\tBUG: Kernel NULL pointer dereference on read at 0x00000000\n\tFaulting instruction address: 0xc0080000016189f8\n\tOops: Kernel access of bad area, sig: 11 [#1]\n\t...\n\tNIP [c0080000016189f8] ibmvnic_xmit+0x60/0xb60 [ibmvnic]\n\tLR [c000000000c0046c] dev_hard_start_xmit+0x11c/0x280\n\tCall Trace:\n\t[c008000001618f08] ibmvnic_xmit+0x570/0xb60 [ibmvnic] (unreliable)\n\t[c000000000c0046c] dev_hard_start_xmit+0x11c/0x280\n\t[c000000000c9cfcc] sch_direct_xmit+0xec/0x330\n\t[c000000000bfe640] __dev_xmit_skb+0x3a0/0x9d0\n\t[c000000000c00ad4] __dev_queue_xmit+0x394/0x730\n\t[c008000002db813c] __bond_start_xmit+0x254/0x450 [bonding]\n\t[c008000002db8378] bond_start_xmit+0x40/0xc0 [bonding]\n\t[c000000000c0046c] dev_hard_start_xmit+0x11c/0x280\n\t[c000000000c00ca4] __dev_queue_xmit+0x564/0x730\n\t[c000000000cf97e0] neigh_hh_output+0xd0/0x180\n\t[c000000000cfa69c] ip_finish_output2+0x31c/0x5c0\n\t[c000000000cfd244] __ip_queue_xmit+0x194/0x4f0\n\t[c000000000d2a3c4] __tcp_transmit_skb+0x434/0x9b0\n\t[c000000000d2d1e0] __tcp_retransmit_skb+0x1d0/0x6a0\n\t[c000000000d2d984] tcp_retransmit_skb+0x34/0x130\n\t[c000000000d310e8] tcp_retransmit_timer+0x388/0x6d0\n\t[c000000000d315ec] tcp_write_timer_handler+0x1bc/0x330\n\t[c000000000d317bc] tcp_write_timer+0x5c/0x200\n\t[c000000000243270] call_timer_fn+0x50/0x1c0\n\t[c000000000243704] __run_timers.part.0+0x324/0x460\n\t[c000000000243894] run_timer_softirq+0x54/0xa0\n\t[c000000000ea713c] __do_softirq+0x15c/0x3e0\n\t[c000000000166258] __irq_exit_rcu+0x158/0x190\n\t[c000000000166420] irq_exit+0x20/0x40\n\t[c00000000002853c] timer_interrupt+0x14c/0x2b0\n\t[c000000000009a00] decrementer_common_virt+0x210/0x220\n\t--- interrupt: 900 at plpar_hcall_norets_notrace+0x18/0x2c\n\nThe immediate cause of the crash is the access of tx_scrq in the following\nsnippet during a reset, where the tx_scrq can be either NULL or an address\nthat will soon be invalid:\n\n\tibmvnic_xmit()\n\t{\n\t\t...\n\t\ttx_scrq = adapter->tx_scrq[queue_num];\n\t\ttxq = netdev_get_tx_queue(netdev, queue_num);\n\t\tind_bufp = &tx_scrq->ind_buf;\n\n\t\tif (test_bit(0, &adapter->resetting)) {\n\t\t...\n\t}\n\nBut beyond that, the call to ibmvnic_xmit() itself is not safe during a\nreset and the reset path attempts to avoid this by stopping the queue in\nibmvnic_cleanup(). However just after the queue was stopped, an in-flight\nibmvnic_complete_tx() could have restarted the queue even as the reset is\nprogressing.\n\nSince the queue was restarted we could get a call to ibmvnic_xmit() which\ncan then access the bad tx_scrq (or other fields).\n\nWe cannot however simply have ibmvnic_complete_tx() check the ->resetting\nbit and skip starting the queue. This can race at the \"back-end\" of a good\nreset which just restarted the queue but has not cleared the ->resetting\nbit yet. If we skip restarting the queue due to ->resetting being true,\nthe queue would remain stopped indefinitely potentially leading to transmit\ntimeouts.\n\nIOW ->resetting is too broad for this purpose. Instead use a new flag\nthat indicates whether or not the queues are active. Only the open/\nreset paths control when the queues are active. ibmvnic_complete_tx()\nand others wake up the queue only if the queue is marked active.\n\nSo we will have:\n\tA. reset/open thread in ibmvnic_cleanup() and __ibmvnic_open()\n\n\t\t->resetting = true\n\t\t->tx_queues_active = false\n\t\tdisable tx queues\n\t\t...\n\t\t->tx_queues_active = true\n\t\tstart tx queues\n\n\tB. Tx interrupt in ibmvnic_complete_tx():\n\n\t\tif (->tx_queues_active)\n\t\t\tnetif_wake_subqueue();\n\nTo ensure that ->tx_queues_active and state of the queues are consistent,\nwe need a lock which:\n\n\t- must also be taken in the interrupt path (ibmvnic_complete_tx())\n\t- shared across the multiple\n---truncated---"
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ibmvnic: se corrige la ejecución entre xmit y reset Existe una ejecución entre reset y las rutas de transmisión que puede provocar que ibmvnic_xmit() acceda a un scrq después de que se haya liberado en la ruta de reset. Puede provocar un bloqueo como: El kernel intentó leer la página del usuario (0): ¿intento de explotación? (uid: 0) ERROR: Desreferencia de puntero NULL del kernel en lectura en 0x00000000 Dirección de instrucción con error: 0xc0080000016189f8 Oops: Acceso del kernel al área defectuosa, sig: 11 [#1] ... NIP [c0080000016189f8] ibmvnic_xmit+0x60/0xb60 [ibmvnic] LR [c000000000c0046c] dev_hard_start_xmit+0x11c/0x280 Rastreo de llamadas: [c008000001618f08] ibmvnic_xmit+0x570/0xb60 [ibmvnic] (no confiable) [c000000000c0046c] dev_hard_start_xmit+0x11c/0x280 [c000000000c9cfcc] sch_direct_xmit+0xec/0x330 [c000000000bfe640] __dev_xmit_skb+0x3a0/0x9d0 [c000000000c00ad4] __dev_queue_xmit+0x394/0x730 [c008000002db813c] __bond_start_xmit+0x254/0x450 [enlace] [c008000002db8378] bond_start_xmit+0x40/0xc0 [enlace] [c000000000c0046c] dev_hard_start_xmit+0x11c/0x280 [c000000000c00ca4] __dev_queue_xmit+0x564/0x730 [c000000000cf97e0] neigh_hh_output+0xd0/0x180 [c000000000cfa69c] ip_finish_output2+0x31c/0x5c0 [c000000000cfd244] __ip_queue_xmit+0x194/0x4f0 [c000000000d2a3c4] __tcp_transmit_skb+0x434/0x9b0 [c000000000d2d1e0] __tcp_retransmit_skb+0x1d0/0x6a0 [c000000000d2d984] tcp_retransmit_skb+0x34/0x130 [c000000000d310e8] tcp_retransmit_timer+0x388/0x6d0 [c000000000d315ec] tcp_write_timer_handler+0x1bc/0x330 [c000000000d317bc] tcp_write_timer+0x5c/0x200 [c000000000243270] call_timer_fn+0x50/0x1c0 [c000000000243704] __run_timers.part.0+0x324/0x460 [c000000000243894] run_timer_softirq+0x54/0xa0 [c000000000ea713c] __do_softirq+0x15c/0x3e0 [c000000000166258] __irq_exit_rcu+0x158/0x190 [c000000000166420] irq_exit+0x20/0x40 [c00000000002853c] timer_interrupt+0x14c/0x2b0 [c000000000009a00] decrementer_common_virt+0x210/0x220 --- interrupción: 900 La causa inmediata del bloqueo es el acceso a tx_scrq en el siguiente fragmento durante un reinicio, donde tx_scrq puede ser NULL o una dirección que pronto será inválida: ibmvnic_xmit() { ... tx_scrq = adaptador->tx_scrq[queue_num]; txq = netdev_get_tx_queue(netdev, queue_num); ind_bufp = &tx_scrq->ind_buf; if (test_bit(0, &adapter->resetting)) { ... } Pero más allá de eso, la llamada a ibmvnic_xmit() en sí no es segura durante un reinicio y la ruta de reinicio intenta evitar esto deteniendo la cola en ibmvnic_cleanup(). Sin embargo, justo después de que se detuviera la cola, una ibmvnic_complete_tx() en curso podría haber reiniciado la cola incluso mientras el reinicio estaba en progreso. Dado que la cola se reinició, podríamos recibir una llamada a ibmvnic_xmit() que luego puede acceder al tx_scrq incorrecto (u otros campos). Sin embargo, no podemos simplemente hacer que ibmvnic_complete_tx() verifique el bit ->resetting y omita el inicio de la cola. Esto puede funcionar en el \"back-end\" de un reinicio correcto que simplemente reinició la cola pero aún no borró el bit ->resetting. Si omitimos el reinicio de la cola debido a que ->resetting es verdadero, la cola permanecería detenida indefinidamente, lo que podría provocar tiempos de espera de transmisión. IOW ->resetting es demasiado amplio para este propósito. En su lugar, use un nuevo indicador que indique si las colas están activas o no. Solo las rutas de apertura/reinicio controlan cuándo están activas las colas. ibmvnic_complete_tx() y otros activan la cola solo si la cola está marcada como activa. Por lo tanto, tendremos: A. restablecer/abrir subproceso en ibmvnic_cleanup() y __ibmvnic_open() ->resetting = true ->tx_queues_active = false deshabilitar colas de transmisión ... ->tx_queues_active = true iniciar colas de transmisión B. Interrupción de transmisión en ibmvnic_complete_tx(): if (->tx_queues_active) netif_wake_subqueue(); Para garantizar que ->tx_queues_active y el estado de las colas sean cons ---truncado---"
}
],
"lastModified": "2026-08-04T10:17:38.677",
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