mirror of
https://github.com/fkie-cad/nvd-json-data-feeds.git
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93 lines
8.0 KiB
JSON
93 lines
8.0 KiB
JSON
{
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"id": "CVE-2022-48760",
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"published": "2024-06-20T12:15:14.110",
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"lastModified": "2024-11-21T07:33:57.913",
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"vulnStatus": "Awaiting Analysis",
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"cveTags": [],
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nUSB: core: Fix hang in usb_kill_urb by adding memory barriers\n\nThe syzbot fuzzer has identified a bug in which processes hang waiting\nfor usb_kill_urb() to return. It turns out the issue is not unlinking\nthe URB; that works just fine. Rather, the problem arises when the\nwakeup notification that the URB has completed is not received.\n\nThe reason is memory-access ordering on SMP systems. In outline form,\nusb_kill_urb() and __usb_hcd_giveback_urb() operating concurrently on\ndifferent CPUs perform the following actions:\n\nCPU 0\t\t\t\t\tCPU 1\n----------------------------\t\t---------------------------------\nusb_kill_urb():\t\t\t\t__usb_hcd_giveback_urb():\n ...\t\t\t\t\t ...\n atomic_inc(&urb->reject);\t\t atomic_dec(&urb->use_count);\n ...\t\t\t\t\t ...\n wait_event(usb_kill_urb_queue,\n\tatomic_read(&urb->use_count) == 0);\n\t\t\t\t\t if (atomic_read(&urb->reject))\n\t\t\t\t\t\twake_up(&usb_kill_urb_queue);\n\nConfining your attention to urb->reject and urb->use_count, you can\nsee that the overall pattern of accesses on CPU 0 is:\n\n\twrite urb->reject, then read urb->use_count;\n\nwhereas the overall pattern of accesses on CPU 1 is:\n\n\twrite urb->use_count, then read urb->reject.\n\nThis pattern is referred to in memory-model circles as SB (for \"Store\nBuffering\"), and it is well known that without suitable enforcement of\nthe desired order of accesses -- in the form of memory barriers -- it\nis entirely possible for one or both CPUs to execute their reads ahead\nof their writes. The end result will be that sometimes CPU 0 sees the\nold un-decremented value of urb->use_count while CPU 1 sees the old\nun-incremented value of urb->reject. Consequently CPU 0 ends up on\nthe wait queue and never gets woken up, leading to the observed hang\nin usb_kill_urb().\n\nThe same pattern of accesses occurs in usb_poison_urb() and the\nfailure pathway of usb_hcd_submit_urb().\n\nThe problem is fixed by adding suitable memory barriers. To provide\nproper memory-access ordering in the SB pattern, a full barrier is\nrequired on both CPUs. The atomic_inc() and atomic_dec() accesses\nthemselves don't provide any memory ordering, but since they are\npresent, we can use the optimized smp_mb__after_atomic() memory\nbarrier in the various routines to obtain the desired effect.\n\nThis patch adds the necessary memory barriers."
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},
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{
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"lang": "es",
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"value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: USB: core: corrige el bloqueo en usb_kill_urb agregando barreras de memoria el syzbot fuzzer ha identificado un error en el que los procesos se bloquean esperando que regrese usb_kill_urb(). Resulta que el problema no es desvincular la URB; eso funciona bien. M\u00e1s bien, el problema surge cuando no se recibe la notificaci\u00f3n de activaci\u00f3n de que la URB ha completado. El motivo son los pedidos de acceso a la memoria en los sistemas SMP. En forma resumida, usb_kill_urb() y __usb_hcd_giveback_urb() operando simult\u00e1neamente en diferentes CPU realizan las siguientes acciones: CPU 0 CPU 1 ------------------------- --- --------------------------------- usb_kill_urb(): __usb_hcd_giveback_urb(): ... ... atomic_inc(&urb->rechazar); atomic_dec(&urb->use_count); ... ... wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0); if (atomic_read(&urb->reject)) wake_up(&usb_kill_urb_queue); Limitando su atenci\u00f3n a urb->reject y urb->use_count, puede ver que el patr\u00f3n general de accesos en la CPU 0 es: escribir urb->reject, luego leer urb->use_count; mientras que el patr\u00f3n general de accesos en la CPU 1 es: escribir urb->use_count, luego leer urb->reject. En los c\u00edrculos de modelos de memoria se hace referencia a este patr\u00f3n como SB (por \"Store Buffering\"), y es bien sabido que sin una aplicaci\u00f3n adecuada del orden deseado de accesos (en forma de barreras de memoria) es completamente posible que una o ambas CPU para ejecutar sus lecturas antes de sus escrituras. El resultado final ser\u00e1 que a veces la CPU 0 ve el antiguo valor no incrementado de urb->use_count mientras que la CPU 1 ve el antiguo valor no incrementado de urb->reject. En consecuencia, la CPU 0 termina en la cola de espera y nunca se activa, lo que provoca el bloqueo observado en usb_kill_urb(). El mismo patr\u00f3n de accesos ocurre en usb_poison_urb() y la ruta de falla de usb_hcd_submit_urb(). El problema se soluciona agregando barreras de memoria adecuadas. Para proporcionar un orden adecuado de acceso a la memoria en el patr\u00f3n SB, se requiere una barrera completa en ambas CPU. Los accesos atomic_inc() y atomic_dec() en s\u00ed no proporcionan ning\u00fan orden de memoria, pero como est\u00e1n presentes, podemos usar la barrera de memoria optimizada smp_mb__after_atomic() en las distintas rutinas para obtener el efecto deseado. Este parche agrega las barreras de memoria necesarias."
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}
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],
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"metrics": {},
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/26fbe9772b8c459687930511444ce443011f86bf",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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},
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{
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"url": "https://git.kernel.org/stable/c/546ba238535d925254e0b3f12012a5c55801e2f3",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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},
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{
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"url": "https://git.kernel.org/stable/c/5904dfd3ddaff3bf4a41c3baf0a8e8f31ed4599b",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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},
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{
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"url": "https://git.kernel.org/stable/c/5f138ef224dffd15d5e5c5b095859719e0038427",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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},
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{
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"url": "https://git.kernel.org/stable/c/9340226388c66a7e090ebb00e91ed64a753b6c26",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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},
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{
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"url": "https://git.kernel.org/stable/c/9c61fce322ac2ef7fecf025285353570d60e41d6",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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},
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{
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"url": "https://git.kernel.org/stable/c/b50f5ca60475710bbc9a3af32fbfc17b1e69c2f0",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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},
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{
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"url": "https://git.kernel.org/stable/c/c9a18f7c5b071dce5e6939568829d40994866ab0",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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},
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{
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"url": "https://git.kernel.org/stable/c/e3b131e30e612ff0e32de6c1cb4f69f89db29193",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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},
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{
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"url": "https://git.kernel.org/stable/c/26fbe9772b8c459687930511444ce443011f86bf",
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"source": "af854a3a-2127-422b-91ae-364da2661108"
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},
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{
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"url": "https://git.kernel.org/stable/c/546ba238535d925254e0b3f12012a5c55801e2f3",
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"source": "af854a3a-2127-422b-91ae-364da2661108"
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},
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{
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"url": "https://git.kernel.org/stable/c/5904dfd3ddaff3bf4a41c3baf0a8e8f31ed4599b",
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"source": "af854a3a-2127-422b-91ae-364da2661108"
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},
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{
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"url": "https://git.kernel.org/stable/c/5f138ef224dffd15d5e5c5b095859719e0038427",
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"source": "af854a3a-2127-422b-91ae-364da2661108"
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},
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{
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"url": "https://git.kernel.org/stable/c/9340226388c66a7e090ebb00e91ed64a753b6c26",
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"source": "af854a3a-2127-422b-91ae-364da2661108"
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},
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{
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"url": "https://git.kernel.org/stable/c/9c61fce322ac2ef7fecf025285353570d60e41d6",
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"source": "af854a3a-2127-422b-91ae-364da2661108"
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},
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{
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"url": "https://git.kernel.org/stable/c/b50f5ca60475710bbc9a3af32fbfc17b1e69c2f0",
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"source": "af854a3a-2127-422b-91ae-364da2661108"
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},
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{
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"url": "https://git.kernel.org/stable/c/c9a18f7c5b071dce5e6939568829d40994866ab0",
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"source": "af854a3a-2127-422b-91ae-364da2661108"
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},
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{
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"url": "https://git.kernel.org/stable/c/e3b131e30e612ff0e32de6c1cb4f69f89db29193",
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"source": "af854a3a-2127-422b-91ae-364da2661108"
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}
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]
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} |