In the Linux kernel, the following vulnerability has been resolved: ext4: dax: fix overflowing extents beyond inode size when partially writing The dax_iomap_rw() does two things in each iteration: map written blocks and copy user data to blocks. If the process is killed by user(See signal handling in dax_iomap_iter()), the copied data will be returned and added on inode size, which means that the length of written extents may exceed the inode size, then fsck will fail. An example is given as: dd if=/dev/urandom of=file bs=4M count=1 dax_iomap_rw iomap_iter // round 1 ext4_iomap_begin ext4_iomap_alloc // allocate 0~2M extents(written flag) dax_iomap_iter // copy 2M data iomap_iter // round 2 iomap_iter_advance iter->pos += iter->processed // iter->pos = 2M ext4_iomap_begin ext4_iomap_alloc // allocate 2~4M extents(written flag) dax_iomap_iter fatal_signal_pending done = iter->pos - iocb->ki_pos // done = 2M ext4_handle_inode_extension ext4_update_inode_size // inode size = 2M fsck reports: Inode 13, i_size is 2097152, should be 4194304. Fix? Fix the problem by truncating extents if the written length is smaller than expected.
En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: dax: se corrige el desbordamiento de extensiones más allá del tamaño del inodo al escribir parcialmente. Dax_iomap_rw() hace dos cosas en cada iteración: asigna bloques escritos y copia datos de usuario a bloques. Si el usuario finaliza el proceso (consulte el manejo de señales en dax_iomap_iter()), los datos copiados se devolverán y se agregarán al tamaño del inodo, lo que significa que la longitud de las extensiones escritas puede exceder el tamaño del inodo, entonces fsck fallará. Se proporciona un ejemplo como: dd if=/dev/urandom of=file bs=4M count=1 dax_iomap_rw iomap_iter // ronda 1 ext4_iomap_begin ext4_iomap_alloc // asignar 0~2M de extensiones (bandera escrita) dax_iomap_iter // copiar 2M de datos iomap_iter // ronda 2 iomap_iter_advance iter->pos += iter->processed // iter->pos = 2M ext4_iomap_begin ext4_iomap_alloc // asignar 2~4M de extensiones (bandera escrita) dax_iomap_iter fatal_signal_pending hecho = iter->pos - iocb->ki_pos // hecho = 2M ext4_handle_inode_extension ext4_update_inode_size // tamaño de inodo = 2M fsck informa: Inodo 13, i_size es 2097152, debería ser 4194304. ¿Solución? Solucione el problema truncando las extensiones si la longitud escrita es menor a la esperada.
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
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| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd360615180> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd2d82dc940> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd38468a000> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd2d82dc3c0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd360617cc0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x7fd2d82dc340> | 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:*:*:*:*:*:*:*:* |