Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2024-49883

Disclosure Date: October 21, 2024 •
CVE-2024-49883 CVSS v3 Base Score: 7.8
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

In the Linux kernel, the following vulnerability has been resolved:

ext4: aovid use-after-free in ext4_ext_insert_extent()

As Ojaswin mentioned in Link, in ext4_ext_insert_extent(), if the path is
reallocated in ext4_ext_create_new_leaf(), we’ll use the stale path and
cause UAF. Below is a sample trace with dummy values:

ext4_ext_insert_extent
path = *ppath = 2000
ext4_ext_create_new_leaf(ppath)

ext4_find_extent(ppath)
  path = *ppath = 2000
  if (depth > path[0].p_maxdepth)
        kfree(path = 2000);
        *ppath = path = NULL;
  path = kcalloc() = 3000
  *ppath = 3000;
  return path;

/* here path is still 2000, UAF! */
eh = path[depth].p_hdr

==================================================================
BUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x26d4/0x3330
Read of size 8 at addr ffff8881027bf7d0 by task kworker/u36:1/179
CPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 Not tainted 6.11.0-rc2-dirty #866
Call Trace:
<TASK>
ext4_ext_insert_extent+0x26d4/0x3330
ext4_ext_map_blocks+0xe22/0x2d40
ext4_map_blocks+0x71e/0x1700
ext4_do_writepages+0x1290/0x2800
[…]

Allocated by task 179:
ext4_find_extent+0x81c/0x1f70
ext4_ext_map_blocks+0x146/0x2d40
ext4_map_blocks+0x71e/0x1700
ext4_do_writepages+0x1290/0x2800
ext4_writepages+0x26d/0x4e0
do_writepages+0x175/0x700
[…]

Freed by task 179:
kfree+0xcb/0x240
ext4_find_extent+0x7c0/0x1f70
ext4_ext_insert_extent+0xa26/0x3330
ext4_ext_map_blocks+0xe22/0x2d40
ext4_map_blocks+0x71e/0x1700
ext4_do_writepages+0x1290/0x2800
ext4_writepages+0x26d/0x4e0
do_writepages+0x175/0x700

[…]

So use *ppath to update the path to avoid the above problem.

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CVSS V3 Severity and Metrics
Base Score:
7.8 High
Impact Score:
5.9
Exploitability Score:
1.8
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
Linux e17ebe4fdd76
Linux not down converted
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • linux

Products

  • linux kernel
Technical Analysis