CVE-2024-47679

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2024-47679
In the Linux kernel, the following vulnerability has been resolved: vfs: fix race between evice_inodes() and find_inode()&iput() Hi, all Recently I noticed a bug[1] in btrfs, after digged it into and I believe it'a race in vfs. Let's assume there's a inode (ie ino 261) with i_count 1 is called by iput(), and there's a concurrent thread calling generic_shutdown_super(). cpu0: cpu1: iput() // i_count is 1 ->spin_lock(inode) ->dec i_count to 0 ->iput_final() generic_shutdown_super() ->__inode_add_lru() ->evict_inodes() // cause some reason[2] ->if (atomic_read(inode->i_count)) continue; // return before // inode 261 passed the above check // list_lru_add_obj() // and then schedule out ->spin_unlock() // note here: the inode 261 // was still at sb list and hash list, // and I_FREEING|I_WILL_FREE was not been set btrfs_iget() // after some function calls ->find_inode() // found the above inode 261 ->spin_lock(inode) // check I_FREEING|I_WILL_FREE // and passed ->__iget() ->spin_unlock(inode) // schedule back ->spin_lock(inode) // check (I_NEW|I_FREEING|I_WILL_FREE) flags, // passed and set I_FREEING iput() ->spin_unlock(inode) ->spin_lock(inode) ->evict() // dec i_count to 0 ->iput_final() ->spin_unlock() ->evict() Now, we have two threads simultaneously evicting the same inode, which may trigger the BUG(inode->i_state & I_CLEAR) statement both within clear_inode() and iput(). To fix the bug, recheck the inode->i_count after holding i_lock. Because in the most scenarios, the first check is valid, and the overhead of spin_lock() can be reduced. If there is any misunderstanding, please let me know, thanks. [1]: https://lore.kernel.org/linux-btrfs/000000000000eabe1d0619c48986@google.com/ [2]: The reason might be 1. SB_ACTIVE was removed or 2. mapping_shrinkable() return false when I reproduced the bug.

4.7 /10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 1.0 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity HIGH

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References
Link Resource
https://git.kernel.org/stable/c/0eed942bc65de1f93eca7bda51344290f9c573bb Patch
https://git.kernel.org/stable/c/0f8a5b6d0dafa4f533ac82e98f8b812073a7c9d1 Patch
https://git.kernel.org/stable/c/3721a69403291e2514d13a7c3af50a006ea1153b Patch
https://git.kernel.org/stable/c/47a68c75052a660e4c37de41e321582ec9496195 Patch
https://git.kernel.org/stable/c/489faddb1ae75b0e1a741fe5ca2542a2b5e794a5
https://git.kernel.org/stable/c/540fb13120c9eab3ef203f90c00c8e69f37449d1 Patch
https://git.kernel.org/stable/c/6c857fb12b9137fee574443385d53914356bbe11 Patch
https://git.kernel.org/stable/c/6cc13a80a26e6b48f78c725c01b91987d61563ef
https://git.kernel.org/stable/c/88b1afbf0f6b221f6c5bb66cc80cd3b38d696687 Patch
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
History

08 Nov 2024, 16:15

Type Values Removed Values Added
References
  • () https://git.kernel.org/stable/c/489faddb1ae75b0e1a741fe5ca2542a2b5e794a5 -
  • () https://git.kernel.org/stable/c/6cc13a80a26e6b48f78c725c01b91987d61563ef -

23 Oct 2024, 14:49

Type Values Removed Values Added
CPE cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
First Time Linux linux Kernel
Linux
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 4.7
Summary
  • (es) En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: vfs: arregla la ejecución entre evice_inodes() y find_inode()&iput() Hola a todos Recientemente noté un error[1] en btrfs, después de investigarlo y creo que es una ejecución en vfs. Supongamos que hay un inodo (es decir, ino 261) con i_count 1 que es llamado por iput(), y hay un hilo concurrente que llama a generic_shutdown_super(). cpu0: cpu1: iput() // i_count es 1 ->spin_lock(inode) ->dec i_count a 0 ->iput_final() generic_shutdown_super() ->__inode_add_lru() ->evict_inodes() // por alguna razón[2] ->if (atomic_read(inode->i_count)) continue; // regresar antes // el inodo 261 pasó la verificación anterior // list_lru_add_obj() // y luego programar la salida ->spin_unlock() // nota aquí: el inodo 261 // todavía estaba en la lista sb y la lista hash, // y I_FREEING|I_WILL_FREE no se había establecido btrfs_iget() // después de algunas llamadas de función ->find_inode() // encontró el inodo 261 anterior ->spin_lock(inode) // verificó I_FREEING|I_WILL_FREE // y pasó ->__iget() ->spin_unlock(inode) // programó de regreso ->spin_lock(inode) // verificó los indicadores (I_NEW|I_FREEING|I_WILL_FREE), // pasó y estableció I_FREEING iput() ->spin_unlock(inode) ->spin_lock(inode) ->evict() // dec i_count a 0 ->iput_final() ->spin_unlock() ->evict() Ahora, tenemos dos subprocesos expulsando simultáneamente el mismo inodo, lo que puede activar la declaración BUG(inode->i_state & I_CLEAR) tanto dentro de clear_inode() como de iput(). Para corregir el error, vuelva a verificar inode->i_count después de mantener i_lock. Porque en la mayoría de los escenarios, la primera verificación es válida y se puede reducir la sobrecarga de spin_lock(). Si hay algún malentendido, hágamelo saber, gracias. [1]: https://lore.kernel.org/linux-btrfs/000000000000eabe1d0619c48986@google.com/ [2]: La razón podría ser 1. SB_ACTIVE fue eliminado o 2. mapping_shrinkable() devolvió falso cuando reproduje el error.
References () https://git.kernel.org/stable/c/0eed942bc65de1f93eca7bda51344290f9c573bb - () https://git.kernel.org/stable/c/0eed942bc65de1f93eca7bda51344290f9c573bb - Patch
References () https://git.kernel.org/stable/c/0f8a5b6d0dafa4f533ac82e98f8b812073a7c9d1 - () https://git.kernel.org/stable/c/0f8a5b6d0dafa4f533ac82e98f8b812073a7c9d1 - Patch
References () https://git.kernel.org/stable/c/3721a69403291e2514d13a7c3af50a006ea1153b - () https://git.kernel.org/stable/c/3721a69403291e2514d13a7c3af50a006ea1153b - Patch
References () https://git.kernel.org/stable/c/47a68c75052a660e4c37de41e321582ec9496195 - () https://git.kernel.org/stable/c/47a68c75052a660e4c37de41e321582ec9496195 - Patch
References () https://git.kernel.org/stable/c/540fb13120c9eab3ef203f90c00c8e69f37449d1 - () https://git.kernel.org/stable/c/540fb13120c9eab3ef203f90c00c8e69f37449d1 - Patch
References () https://git.kernel.org/stable/c/6c857fb12b9137fee574443385d53914356bbe11 - () https://git.kernel.org/stable/c/6c857fb12b9137fee574443385d53914356bbe11 - Patch
References () https://git.kernel.org/stable/c/88b1afbf0f6b221f6c5bb66cc80cd3b38d696687 - () https://git.kernel.org/stable/c/88b1afbf0f6b221f6c5bb66cc80cd3b38d696687 - Patch
CWE CWE-362

21 Oct 2024, 12:15

Type Values Removed Values Added
New CVE
Information

Published : 2024-10-21 12:15

Updated : 2024-11-08 16:15

NVD link : CVE-2024-47679

Mitre link : CVE-2024-47679

CVE.ORG link : CVE-2024-47679

JSON object : View

Products Affected

linux

  • linux_kernel
CWE
CWE-362

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')