CVE-2023-52622

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: evita fallos de cambio de tamaño en línea debido a flex bg sobredimensionado Cuando redimensionamos en línea un sistema de archivos ext4 con un flexbg_size sobredimensionado, mkfs.ext4 -F -G 67108864 $dev -b 4096 100M mount $dev $dir resize2fs $dev 16G se activa el siguiente WARN_ON: ===================================== ============================== ADVERTENCIA: CPU: 0 PID: 427 en mm/page_alloc.c:4402 __alloc_pages+0x411/ 0x550 Módulos vinculados en: sg(E) CPU: 0 PID: 427 Comm: resize2fs Contaminado: GE 6.6.0-rc5+ #314 RIP: 0010:__alloc_pages+0x411/0x550 Seguimiento de llamadas: __kmalloc_large_node+0xa2/0x200 __kmalloc+ 0x16e/0x290 text4_resize_fs+0x481/0xd80 __ext4_ioctl+0x1616/0x1d90 text4_ioctl+0x12/0x20 __x64_sys_ioctl+0xf0/0x150 do_syscall_64+0x3b/0x90 ======== =============== ============================================ Esto se debe a que flexbg_size también lo es grande y el tamaño de la matriz new_group_data que se asignará excede MAX_ORDER. Actualmente, el valor mínimo de MAX_ORDER es 8, el valor mínimo de PAGE_SIZE es 4096, el número máximo correspondiente de grupos que se pueden asignar es: (PAGE_SIZE << MAX_ORDER) / sizeof(struct text4_new_group_data) ? 21845 Y el valor que está hacia abajo -alineado a la potencia de 2 es 16384. Por lo tanto, este valor se define como MAX_RESIZE_BG, y el número de grupos agregados cada vez no excede este valor durante el cambio de tamaño y se agrega varias veces para completar el cambio de tamaño en línea. La diferencia es que los metadatos en flex_bg pueden estar más dispersos.

In the Linux kernel, the following vulnerability has been resolved: ext4: avoid online resizing failures due to oversized flex bg When we online resize an ext4 filesystem with a oversized flexbg_size, mkfs.ext4 -F -G 67108864 $dev -b 4096 100M mount $dev $dir resize2fs $dev 16G the following WARN_ON is triggered: ================================================================== WARNING: CPU: 0 PID: 427 at mm/page_alloc.c:4402 __alloc_pages+0x411/0x550 Modules linked in: sg(E) CPU: 0 PID: 427 Comm: resize2fs Tainted: G E 6.6.0-rc5+ #314 RIP: 0010:__alloc_pages+0x411/0x550 Call Trace: <TASK> __kmalloc_large_node+0xa2/0x200 __kmalloc+0x16e/0x290 ext4_resize_fs+0x481/0xd80 __ext4_ioctl+0x1616/0x1d90 ext4_ioctl+0x12/0x20 __x64_sys_ioctl+0xf0/0x150 do_syscall_64+0x3b/0x90 ================================================================== This is because flexbg_size is too large and the size of the new_group_data array to be allocated exceeds MAX_ORDER. Currently, the minimum value of MAX_ORDER is 8, the minimum value of PAGE_SIZE is 4096, the corresponding maximum number of groups that can be allocated is: (PAGE_SIZE << MAX_ORDER) / sizeof(struct ext4_new_group_data) ≈ 21845 And the value that is down-aligned to the power of 2 is 16384. Therefore, this value is defined as MAX_RESIZE_BG, and the number of groups added each time does not exceed this value during resizing, and is added multiple times to complete the online resizing. The difference is that the metadata in a flex_bg may be more dispersed.

It was discovered that the Open vSwitch implementation in the Linux kernel could overflow its stack during recursive action operations under certain conditions. A local attacker could use this to cause a denial of service. Sander Wiebing, Alvise de Faveri Tron, Herbert Bos, and Cristiano Giuffrida discovered that the Linux kernel mitigations for the initial Branch History Injection vulnerability were insufficient for Intel processors. A local attacker could potentially use this to expose sensitive information.