CVE-2024-49883

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

Published Oct 21, 2024 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4008-1 linux-6.1 security update
Debian DLA Debian DLA DLA-4075-1 linux security update
Ubuntu USN Ubuntu USN USN-7166-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7166-2 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7166-3 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7166-4 Linux kernel (Xilinx ZynqMP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7186-1 Linux kernel (Intel IoTG) vulnerabilities
Ubuntu USN Ubuntu USN USN-7186-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7194-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7276-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7277-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7293-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7294-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7294-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7294-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7294-4 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7295-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7301-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7303-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7303-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7303-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7304-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7310-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7311-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7384-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7384-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7385-1 Linux kernel (IBM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7386-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-7393-1 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7401-1 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7403-1 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-7413-1 Linux kernel (IoT) vulnerabilities
Ubuntu USN Ubuntu USN USN-7468-1 Linux kernel (Azure, N-Series) vulnerabilities
Ubuntu USN Ubuntu USN USN-7539-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7540-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-7684-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7684-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7684-3 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7685-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7685-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7685-3 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7685-4 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-7685-5 Linux kernel (Oracle) vulnerabilities
History
Type Values Removed Values Added
First Time appeared Debian
Debian debian Linux
CPEs cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
Vendors & Products Debian
Debian debian Linux
Type Values Removed Values Added
First Time appeared Redhat
Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-416
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title ext4: aovid use-after-free in ext4_ext_insert_extent()
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Aug 5, 2026, 11:40 AM
Reserved
Oct 21, 2024, 12:17 PM
Status
Modified
Published
Oct 21, 2024, 6:15 PM
Modified
Aug 4, 2026, 11:20 AM
Severity
Moderate
Public date
Oct 21, 2024, 12:00 AM