CVE-2023-52451

En el kernel de Linux, se resolvió la siguiente vulnerabilidad: powerpc/pseries/memhp: corrige el acceso más allá del final de la matriz drmem dlpar_memory_remove_by_index() puede acceder más allá de los límites de la matriz lmb drmem cuando la búsqueda de LMB no coincide con una entrada con el valor dado Índice de la República Democrática del Congo. Cuando la búsqueda falla, el cursor queda apuntando a &drmem_info->lmbs[drmem_info->n_lmbs], que es un elemento después de la última entrada válida en la matriz. El mensaje de depuración al final de la función elimina la referencia a este puntero: pr_debug("Error al eliminar memoria en caliente en %llx
", lmb->base_addr); Esto se encontró mediante inspección y se confirmó con KASAN: pseries-hotplug-mem: Intentando eliminar LMB en caliente, índice drc 1234 ========================== ========================================== ERROR: KASAN: losa- fuera de límites en dlpar_memory+0x298/0x1658 Lectura de tamaño 8 en la dirección c000000364e97fd0 por tarea bash/949 dump_stack_lvl+0xa4/0xfc (no confiable) print_report+0x214/0x63c kasan_report+0x140/0x2e0 __asan_load8+0xa8/ 0xe0 dlpar_memory+0x298/0x1658 handle_dlpar_errorlog +0x130/0x1d0 dlpar_store+0x18c/0x3e0 kobj_attr_store+0x68/0xa0 sysfs_kf_write+0xc4/0x110 kernfs_fop_write_iter+0x26c/0x390 vfs_write+0x2d4/0x4e0 ksys_write+0xac/0x1a0 system_call_exception+0x268/0x530 system_call_vectored_common+0x15c/0x2ec Asignado por tarea 1: kasan_save_stack +0x48/0x80 kasan_set_track+0x34/0x50 kasan_save_alloc_info+0x34/0x50 __kasan_kmalloc+0xd0/0x120 __kmalloc+0x8c/0x320 kmalloc_array.constprop.0+0x48/0x5c drmem_init+0x2a0/0x41c do_one _initcall+0xe0/0x5c0 kernel_init_freeable+0x4ec/0x5a0 kernel_init+ 0x30/0x1e0 ret_from_kernel_user_thread+0x14/0x1c La dirección con errores pertenece al objeto en c000000364e80000 que pertenece al caché kmalloc-128k de tamaño 131072 La dirección con errores se encuentra 0 bytes a la derecha de la región asignada de 98256 bytes [c000000364e80000, c0 00000364e97fd0) = ==================================================== =============== pseries-hotplug-mem: No se pudo eliminar la memoria en caliente en 0 Registre las búsquedas fallidas con un mensaje separado y elimine la referencia del cursor solo cuando apunte a una entrada válida.

In the Linux kernel, the following vulnerability has been resolved: powerpc/pseries/memhp: Fix access beyond end of drmem array dlpar_memory_remove_by_index() may access beyond the bounds of the drmem lmb array when the LMB lookup fails to match an entry with the given DRC index. When the search fails, the cursor is left pointing to &drmem_info->lmbs[drmem_info->n_lmbs], which is one element past the last valid entry in the array. The debug message at the end of the function then dereferences this pointer: pr_debug("Failed to hot-remove memory at %llx
", lmb->base_addr); This was found by inspection and confirmed with KASAN: pseries-hotplug-mem: Attempting to hot-remove LMB, drc index 1234 ================================================================== BUG: KASAN: slab-out-of-bounds in dlpar_memory+0x298/0x1658 Read of size 8 at addr c000000364e97fd0 by task bash/949 dump_stack_lvl+0xa4/0xfc (unreliable) print_report+0x214/0x63c kasan_report+0x140/0x2e0 __asan_load8+0xa8/0xe0 dlpar_memory+0x298/0x1658 handle_dlpar_errorlog+0x130/0x1d0 dlpar_store+0x18c/0x3e0 kobj_attr_store+0x68/0xa0 sysfs_kf_write+0xc4/0x110 kernfs_fop_write_iter+0x26c/0x390 vfs_write+0x2d4/0x4e0 ksys_write+0xac/0x1a0 system_call_exception+0x268/0x530 system_call_vectored_common+0x15c/0x2ec Allocated by task 1: kasan_save_stack+0x48/0x80 kasan_set_track+0x34/0x50 kasan_save_alloc_info+0x34/0x50 __kasan_kmalloc+0xd0/0x120 __kmalloc+0x8c/0x320 kmalloc_array.constprop.0+0x48/0x5c drmem_init+0x2a0/0x41c do_one_initcall+0xe0/0x5c0 kernel_init_freeable+0x4ec/0x5a0 kernel_init+0x30/0x1e0 ret_from_kernel_user_thread+0x14/0x1c The buggy address belongs to the object at c000000364e80000 which belongs to the cache kmalloc-128k of size 131072 The buggy address is located 0 bytes to the right of allocated 98256-byte region [c000000364e80000, c000000364e97fd0) ================================================================== pseries-hotplug-mem: Failed to hot-remove memory at 0 Log failed lookups with a separate message and dereference the cursor only when it points to a valid entry.

Chih-Yen Chang discovered that the KSMBD implementation in the Linux kernel did not properly validate certain data structure fields when parsing lease contexts, leading to an out-of-bounds read vulnerability. A remote attacker could use this to cause a denial of service or possibly expose sensitive information. Quentin Minster discovered that a race condition existed in the KSMBD implementation in the Linux kernel, leading to a use-after-free vulnerability. A remote attacker could use this to cause a denial of service or possibly execute arbitrary code.