ext4: fix potential null deref in ext4_mb_init()
In ext4_mb_init(), ext4_mb_avg_fragment_size_destroy() may be called
when sbi->s_mb_avg_fragment_size remains uninitialized (e.g., if groupinfo
slab cache allocation fails). Since ext4_mb_avg_fragment_size_destroy()
lacks null pointer checking, this leads to a null pointer dereference.
==================================================================
EXT4-fs: no memory for groupinfo slab cache
BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 0 P4D 0
Oops: Oops: 0002 [#1] SMP PTI
CPU:2 UID: 0 PID: 87 Comm:mount Not tainted 6.17.0-rc2 #1134 PREEMPT(none)
RIP: 0010:_raw_spin_lock_irqsave+0x1b/0x40
Call Trace:
<TASK>
xa_destroy+0x61/0x130
ext4_mb_init+0x483/0x540
__ext4_fill_super+0x116d/0x17b0
ext4_fill_super+0xd3/0x280
get_tree_bdev_flags+0x132/0x1d0
vfs_get_tree+0x29/0xd0
do_new_mount+0x197/0x300
__x64_sys_mount+0x116/0x150
do_syscall_64+0x50/0x1c0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
==================================================================
Therefore, add necessary null check to ext4_mb_avg_fragment_size_destroy()
to prevent this issue. The same fix is also applied to
ext4_mb_largest_free_orders_destroy().
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
Sign in to view the affected projects.
| Source | ID | Title |
|---|---|---|
Ubuntu USN |
USN-8029-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8030-1 | Linux kernel (GCP) vulnerabilities |
Ubuntu USN |
USN-8029-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-8048-1 | Linux kernel (OEM) vulnerabilities |
Ubuntu USN |
USN-8029-3 | Linux kernel (Azure) vulnerabilities |
Fri, 13 Mar 2026 17:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Mon, 01 Dec 2025 06:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
Fri, 14 Nov 2025 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Wed, 12 Nov 2025 23:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Vendors & Products |
Linux
Linux linux Kernel |
Wed, 12 Nov 2025 10:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ext4: fix potential null deref in ext4_mb_init() In ext4_mb_init(), ext4_mb_avg_fragment_size_destroy() may be called when sbi->s_mb_avg_fragment_size remains uninitialized (e.g., if groupinfo slab cache allocation fails). Since ext4_mb_avg_fragment_size_destroy() lacks null pointer checking, this leads to a null pointer dereference. ================================================================== EXT4-fs: no memory for groupinfo slab cache BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 0 P4D 0 Oops: Oops: 0002 [#1] SMP PTI CPU:2 UID: 0 PID: 87 Comm:mount Not tainted 6.17.0-rc2 #1134 PREEMPT(none) RIP: 0010:_raw_spin_lock_irqsave+0x1b/0x40 Call Trace: <TASK> xa_destroy+0x61/0x130 ext4_mb_init+0x483/0x540 __ext4_fill_super+0x116d/0x17b0 ext4_fill_super+0xd3/0x280 get_tree_bdev_flags+0x132/0x1d0 vfs_get_tree+0x29/0xd0 do_new_mount+0x197/0x300 __x64_sys_mount+0x116/0x150 do_syscall_64+0x50/0x1c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ================================================================== Therefore, add necessary null check to ext4_mb_avg_fragment_size_destroy() to prevent this issue. The same fix is also applied to ext4_mb_largest_free_orders_destroy(). | |
| Title | ext4: fix potential null deref in ext4_mb_init() | |
| References |
|
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-11T21:43:01.083Z
Reserved: 2025-04-16T07:20:57.168Z
Link: CVE-2025-40119
No data.
Status : Deferred
Published: 2025-11-12T11:15:41.237
Modified: 2026-04-15T00:35:42.020
Link: CVE-2025-40119
OpenCVE Enrichment
Updated: 2025-11-12T22:12:29Z
No weakness.
Ubuntu USN