In the Linux kernel, the following vulnerability has been resolved: scsi: core: Fix unremoved procfs host directory regression Commit fc663711b944 ("scsi: core: Remove the /proc/scsi/${proc_name} directory earlier") fixed a bug related to modules loading/unloading, by adding a call to scsi_proc_hostdir_rm() on scsi_remove_host(). But that led to a potential duplicate call to the hostdir_rm() routine, since it's also called from scsi_host_dev_release(). That triggered a regression report, which was then fixed by commit be03df3d4bfe ("scsi: core: Fix a procfs host directory removal regression"). The fix just dropped the hostdir_rm() call from dev_release(). But it happens that this proc directory is created on scsi_host_alloc(), and that function "pairs" with scsi_host_dev_release(), while scsi_remove_host() pairs with scsi_add_host(). In other words, it seems the reason for removing the proc directory on dev_release() was meant to cover cases in which a SCSI host structure was allocated, but the call to scsi_add_host() didn't happen. And that pattern happens to exist in some error paths, for example. Syzkaller causes that by using USB raw gadget device, error'ing on usb-storage driver, at usb_stor_probe2(). By checking that path, we can see that the BadDevice label leads to a scsi_host_put() after a SCSI host allocation, but there's no call to scsi_add_host() in such path. That leads to messages like this in dmesg (and a leak of the SCSI host proc structure): usb-storage 4-1:87.51: USB Mass Storage device detected proc_dir_entry 'scsi/usb-storage' already registered WARNING: CPU: 1 PID: 3519 at fs/proc/generic.c:377 proc_register+0x347/0x4e0 fs/proc/generic.c:376 The proper fix seems to still call scsi_proc_hostdir_rm() on dev_release(), but guard that with the state check for SHOST_CREATED; there is even a comment in scsi_host_dev_release() detailing that: such conditional is meant for cases where the SCSI host was allocated but there was no calls to {add,remove}_host(), like the usb-storage case. This is what we propose here and with that, the error path of usb-storage does not trigger the warning anymore.
En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: scsi: core: corrige la regresión del directorio del host procfs no eliminado. el commit fc663711b944 ("scsi: core: elimina el directorio /proc/scsi/${proc_name} anteriormente") corrigió un error relacionado con carga/descarga de módulos, agregando una llamada a scsi_proc_hostdir_rm() en scsi_remove_host(). Pero eso llevó a una posible llamada duplicada a la rutina hostdir_rm(), ya que también se llama desde scsi_host_dev_release(). Eso desencadenó un informe de regresión, que luego se solucionó mediante el commit be03df3d4bfe ("scsi: core: Fix a procfs host directorio de eliminación de regresión"). La solución simplemente eliminó la llamada hostdir_rm() desde dev_release(). Pero sucede que este directorio proc se crea en scsi_host_alloc(), y esa función se "empareja" con scsi_host_dev_release(), mientras que scsi_remove_host() se empareja con scsi_add_host(). En otras palabras, parece que la razón para eliminar el directorio proc en dev_release() fue para cubrir casos en los que se asignó una estructura de host SCSI, pero la llamada a scsi_add_host() no ocurrió. Y ese patrón existe en algunas rutas de error, por ejemplo. Syzkaller provoca que, al utilizar un dispositivo USB sin formato, se produzca un error en el controlador de almacenamiento USB, en usb_stor_probe2(). Al verificar esa ruta, podemos ver que la etiqueta BadDevice conduce a scsi_host_put() después de una asignación de host SCSI, pero no hay ninguna llamada a scsi_add_host() en dicha ruta. Eso lleva a mensajes como este en dmesg (y una fuga de la estructura del proceso del host SCSI): usb-storage 4-1:87.51: Dispositivo de almacenamiento masivo USB detectado proc_dir_entry 'scsi/usb-storage' ya registrado ADVERTENCIA: CPU: 1 PID : 3519 en fs/proc/generic.c:377 proc_register+0x347/0x4e0 fs/proc/generic.c:376 La solución adecuada parece seguir llamando a scsi_proc_hostdir_rm() en dev_release(), pero guárdela con la verificación de estado para SHOST_CREATED ; incluso hay un comentario en scsi_host_dev_release() que detalla que: dicho condicional está destinado a casos en los que se asignó el host SCSI pero no hubo llamadas a {add,remove}_host(), como el caso del almacenamiento USB. Esto es lo que proponemos aquí y con eso, la ruta de error del almacenamiento USB ya no activa la advertencia.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
| Attack Vector | LOCAL |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | LOW |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | NONE |
| Integrity Impact | NONE |
| Availability Impact | HIGH |
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
NVD-CWE-noinfo
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd34b8d8640> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd34b8d8b00> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd36b437a80> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd29874a440> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd34b8d9140> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd34b8d9bc0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd36a6a5280> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd38557ccc0> | Operating System |
| linux | linux_kernel | 6.3 | <built-in method update of dict object at 0x7fd386775240> | Operating System |
| linux | linux_kernel | 6.3 | <built-in method update of dict object at 0x7fd34b8d8fc0> | Operating System |
| linux | linux_kernel | 6.3 | <built-in method update of dict object at 0x7fd36b437a00> | Operating System |
| linux | linux_kernel | 6.3 | <built-in method update of dict object at 0x7fd34b8d8940> | Operating System |
| linux | linux_kernel | 6.3 | <built-in method update of dict object at 0x7fd36b436800> | Operating System |
| linux | linux_kernel | 6.3 | <built-in method update of dict object at 0x7fd348bba980> | Operating System |
| linux | linux_kernel | 6.9 | <built-in method update of dict object at 0x7fd37019cec0> | Operating System |
| debian | debian_linux | 10.0 | <built-in method update of dict object at 0x7fd348bbb140> | Operating System |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.3:-:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.3:rc3:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.3:rc4:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.3:rc5:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.3:rc6:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.3:rc7:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.9:rc1:*:*:*:*:*:* |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* |