In the Linux kernel, the following vulnerability has been resolved: ext4: update orig_path in ext4_find_extent() In ext4_find_extent(), if the path is not big enough, we free it and set *orig_path to NULL. But after reallocating and successfully initializing the path, we don't update *orig_path, in which case the caller gets a valid path but a NULL ppath, and this may cause a NULL pointer dereference or a path memory leak. For example: ext4_split_extent path = *ppath = 2000 ext4_find_extent if (depth > path[0].p_maxdepth) kfree(path = 2000); *orig_path = path = NULL; path = kcalloc() = 3000 ext4_split_extent_at(*ppath = NULL) path = *ppath; ex = path[depth].p_ext; // NULL pointer dereference! ================================================================== BUG: kernel NULL pointer dereference, address: 0000000000000010 CPU: 6 UID: 0 PID: 576 Comm: fsstress Not tainted 6.11.0-rc2-dirty #847 RIP: 0010:ext4_split_extent_at+0x6d/0x560 Call Trace: <TASK> ext4_split_extent.isra.0+0xcb/0x1b0 ext4_ext_convert_to_initialized+0x168/0x6c0 ext4_ext_handle_unwritten_extents+0x325/0x4d0 ext4_ext_map_blocks+0x520/0xdb0 ext4_map_blocks+0x2b0/0x690 ext4_iomap_begin+0x20e/0x2c0 [...] ================================================================== Therefore, *orig_path is updated when the extent lookup succeeds, so that the caller can safely use path or *ppath.
En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: actualización de orig_path en ext4_find_extent() En ext4_find_extent(), si la ruta no es lo suficientemente grande, la liberamos y establecemos *orig_path en NULL. Pero después de reasignar e inicializar correctamente la ruta, no actualizamos *orig_path, en cuyo caso el llamador obtiene una ruta válida pero un ppath NULL, y esto puede causar una desreferencia de puntero NULL o una pérdida de memoria de ruta. Por ejemplo: ext4_split_extent path = *ppath = 2000 ext4_find_extent if (depth > path[0].p_maxdepth) kfree(path = 2000); *orig_path = path = NULL; path = kcalloc() = 3000 ext4_split_extent_at(*ppath = NULL) path = *ppath; ex = path[depth].p_ext; // ¡Desreferencia de puntero NULL! ===================================================================== ERROR: Desreferencia de puntero NULL del núcleo, dirección: 000000000000010 CPU: 6 UID: 0 PID: 576 Comm: fsstress No contaminado 6.11.0-rc2-dirty #847 RIP: 0010:ext4_split_extent_at+0x6d/0x560 Rastreo de llamada: ext4_split_extent.isra.0+0xcb/0x1b0 ext4_ext_convert_to_initialized+0x168/0x6c0 ext4_ext_handle_unwritten_extents+0x325/0x4d0 ext4_ext_map_blocks+0x520/0xdb0 ext4_map_blocks+0x2b0/0x690 ext4_iomap_begin+0x20e/0x2c0 [...] ====================================================================== Por lo tanto, *orig_path se actualiza cuando la búsqueda de extensión tiene éxito, de modo que el llamador puede usar path o *ppath de forma segura.
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
CWE-476
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd3686d00c0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd3866587c0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd36b186b40> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd2dbe45f00> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd3686d3180> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd3686d3500> | 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:*:*:*:*:*:*:*:* |