In the Linux kernel, the following vulnerability has been resolved: proc: fix UAF in proc_get_inode() Fix race between rmmod and /proc/XXX's inode instantiation. The bug is that pde->proc_ops don't belong to /proc, it belongs to a module, therefore dereferencing it after /proc entry has been registered is a bug unless use_pde/unuse_pde() pair has been used. use_pde/unuse_pde can be avoided (2 atomic ops!) because pde->proc_ops never changes so information necessary for inode instantiation can be saved _before_ proc_register() in PDE itself and used later, avoiding pde->proc_ops->... dereference. rmmod lookup sys_delete_module proc_lookup_de pde_get(de); proc_get_inode(dir->i_sb, de); mod->exit() proc_remove remove_proc_subtree proc_entry_rundown(de); free_module(mod); if (S_ISREG(inode->i_mode)) if (de->proc_ops->proc_read_iter) --> As module is already freed, will trigger UAF BUG: unable to handle page fault for address: fffffbfff80a702b PGD 817fc4067 P4D 817fc4067 PUD 817fc0067 PMD 102ef4067 PTE 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 26 UID: 0 PID: 2667 Comm: ls Tainted: G Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:proc_get_inode+0x302/0x6e0 RSP: 0018:ffff88811c837998 EFLAGS: 00010a06 RAX: dffffc0000000000 RBX: ffffffffc0538140 RCX: 0000000000000007 RDX: 1ffffffff80a702b RSI: 0000000000000001 RDI: ffffffffc0538158 RBP: ffff8881299a6000 R08: 0000000067bbe1e5 R09: 1ffff11023906f20 R10: ffffffffb560ca07 R11: ffffffffb2b43a58 R12: ffff888105bb78f0 R13: ffff888100518048 R14: ffff8881299a6004 R15: 0000000000000001 FS: 00007f95b9686840(0000) GS:ffff8883af100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffbfff80a702b CR3: 0000000117dd2000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> proc_lookup_de+0x11f/0x2e0 __lookup_slow+0x188/0x350 walk_component+0x2ab/0x4f0 path_lookupat+0x120/0x660 filename_lookup+0x1ce/0x560 vfs_statx+0xac/0x150 __do_sys_newstat+0x96/0x110 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e [[email protected]: don't do 2 atomic ops on the common path]
En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: proc: corrección de UAF en proc_get_inode(). Corrección de la competencia entre rmmod y la instanciación de inodo de /proc/XXX. El error es que pde->proc_ops no pertenece a /proc, sino a un módulo; por lo tanto, desreferenciarlo después de registrar la entrada /proc es un error, a menos que se haya usado el par use_pde/unuse_pde(). Se puede evitar usar_pde/unuse_pde (¡2 operaciones atómicas!) porque pde->proc_ops nunca cambia, de modo que la información necesaria para la instanciación de inodo se puede guardar _antes_ de proc_register() en el propio PDE y usarse más tarde, evitando la desreferencia de pde->proc_ops->... . rmmod lookup sys_delete_module proc_lookup_de pde_get(de); proc_get_inode(dir->i_sb, de); mod->exit() proc_remove eliminar_subárbol_proc proc_entry_rundown(de); liberar_módulo(mod); if (S_ISREG(inode->i_mode)) if (de->proc_ops->proc_read_iter) --> Como el módulo ya está liberado, se activará UAF ERROR: no se puede manejar el error de página para la dirección: fffffbfff80a702b PGD 817fc4067 P4D 817fc4067 PUD 817fc0067 PMD 102ef4067 PTE 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 26 UID: 0 PID: 2667 Comm: ls Tainted: G Nombre del hardware: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:proc_get_inode+0x302/0x6e0 RSP: 0018:ffff88811c837998 EFLAGS: 00010a06 RAX: dffffc0000000000 RBX: fffffffc0538140 RCX: 0000000000000007 RDX: 1ffffffff80a702b RSI: 0000000000000001 RDI: ffffffffc0538158 RBP: ffff8881299a6000 R08: 0000000067bbe1e5 R09: 1ffff11023906f20 R10: ffffffffb560ca07 R11: ffffffffb2b43a58 R12: ffff888105bb78f0 R13: ffff888100518048 R14: ffff8881299a6004 R15: 0000000000000001 FS: 00007f95b9686840(0000) GS:ffff8883af100000(0000) knlGS:000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffbfff80a702b CR3: 0000000117dd2000 CR4: 00000000000006f0 DR0: 00000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Rastreo de llamadas: proc_lookup_de+0x11f/0x2e0 __lookup_slow+0x188/0x350 walk_component+0x2ab/0x4f0 path_lookupat+0x120/0x660 filename_lookup+0x1ce/0x560 vfs_statx+0xac/0x150 __do_sys_newstat+0x96/0x110 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e [[email protected]: no realice 2 operaciones atómicas en la ruta común]
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
| Attack Vector | LOCAL |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | LOW |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | HIGH |
| Integrity Impact | HIGH |
| Availability Impact | HIGH |
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Type: Secondary
Exploitability Score: 1.8
Impact Score: 5.9
| Source | Type | Description |
|---|---|---|
| 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary |
en
CWE-416
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdd6ae980> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdd6af740> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdd6a6c40> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdd6aeec0> | Operating System |
| linux | linux_kernel | 6.14 | <built-in method update of dict object at 0x702bdd6ad880> | Operating System |
| linux | linux_kernel | 6.14 | <built-in method update of dict object at 0x702bdd6afe40> | Operating System |
| linux | linux_kernel | 6.14 | <built-in method update of dict object at 0x702bdd9bcdc0> | Operating System |
| linux | linux_kernel | 6.14 | <built-in method update of dict object at 0x702bdd6ad300> | 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:6.14:rc1:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:* |