ext4: publish jinode after initialization
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 4 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-476.
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: publish jinode after initialization ext4_inode_attach_jinode() publishes ei->jinode to concurrent users. It used to set ei->jinode before jbd2_journal_init_jbd_inode(), allowing a reader to observe a non-NULL jinode with i_vfs_inode still unset. The fast commit flush path can then pass this jinode to jbd2_wait_inode_data(), which dereferences i_vfs_inode->i_mapping and may crash. Below is the crash I observe: ``` BUG: unable to handle page fault for address: 000000010beb47f4 PGD 110e51067 P4D 110e51067 PUD 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 1 UID: 0 PID: 4850 Comm: fc_fsync_bench_ Not tainted 6.18.0-00764-g795a690c06a5 #1 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.17.0-2-2 04/01/2014 RIP: 0010:xas_find_marked+0x3d/0x2e0 Code: e0 03 48 83 f8 02 0f 84 f0 01 00 00 48 8b 47 08 48 89 c3 48 39 c6 0f 82 fd 01 00 00 48 85 c9 74 3d 48 83 f9 03 77 63 4c 8b 0f <49> 8b 71 08 48 c7 47 18 00 00 00 00 48 89 f1 83 e1 03 48 83 f9 02 RSP: 0018:ffffbbee806e7bf0 EFLAGS: 00010246 RAX: 000000000010beb4 RBX: 000000000010beb4 RCX: 0000000000000003 RDX: 0000000000000001 RSI: 0000002000300000 RDI: ffffbbee806e7c10 RBP: 0000000000000001 R08: 0000002000300000 R09: 000000010beb47ec R10: ffff9ea494590090 R11: 0000000000000000 R12: 0000002000300000 R13: ffffbbee806e7c90 R14: ffff9ea494513788 R15: ffffbbee806e7c88 FS: 00007fc2f9e3e6c0(0000) GS:ffff9ea6b1444000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000010beb47f4 CR3: 0000000119ac5000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: <TASK> filemap_get_folios_tag+0x87/0x2a0 __filemap_fdatawait_range+0x5f/0xd0 ? srso_alias_return_thunk+0x5/0xfbef5 ? __schedule+0x3e7/0x10c0 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? preempt_count_sub+0x5f/0x80 ? srso_alias_return_thunk+0x5/0xfbef5 ? cap_safe_nice+0x37/0x70 ? srso_alias_return_thunk+0x5/0xfbef5 ? preempt_count_sub+0x5f/0x80 ? srso_alias_return_thunk+0x5/0xfbef5 filemap_fdatawait_range_keep_errors+0x12/0x40 ext4_fc_commit+0x697/0x8b0 ? ext4_file_write_iter+0x64b/0x950 ? srso_alias_return_thunk+0x5/0xfbef5 ? preempt_count_sub+0x5f/0x80 ? srso_alias_return_thunk+0x5/0xfbef5 ? vfs_write+0x356/0x480 ? srso_alias_return_thunk+0x5/0xfbef5 ? preempt_count_sub+0x5f/0x80 ext4_sync_file+0xf7/0x370 do_fsync+0x3b/0x80 ? syscall_trace_enter+0x108/0x1d0 __x64_sys_fdatasync+0x16/0x20 do_syscall_64+0x62/0x2c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ... ``` Fix this by initializing the jbd2_inode first. Use smp_wmb() and WRITE_ONCE() to publish ei->jinode after initialization. Readers use READ_ONCE() to fetch the pointer.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 3.11 and later | 5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.21, 6.19.11, 7.0 | Patch available | CNA |
- Linux VendorLinux Affected 3.11 and later Fixed in 5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.21, 6.19.11, 7.0 Patch available CNA
CPE configurations NVD · 9
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 3.11.1 to before 5.10.253; 5.11 to before 5.15.203; 5.16 to before 6.1.168; 6.2 to before 6.6.134; 6.7 to before 6.12.81; 6.13 to before 6.18.21; 6.19 to before 6.19.11 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:3.11:-:*:*:*:*:*:* | 3.11 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:3.11:rc6:*:*:*:*:*:* | 3.11 rc6 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:3.11:rc7:*:*:*:*:*:* | 3.11 rc7 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* | 7.0 rc1 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* | 7.0 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* | 7.0 rc3 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* | 7.0 rc4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* | 7.0 rc5 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 3.11.1 to before 5.10.253; 5.11 to before 5.15.203; 5.16 to before 6.1.168; 6.2 to before 6.6.134; 6.7 to before 6.12.81; 6.13 to before 6.18.21; 6.19 to before 6.19.11 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:3.11:-:*:*:*:*:*:* Versions 3.11 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:3.11:rc6:*:*:*:*:*:* Versions 3.11 rc6 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:3.11:rc7:*:*:*:*:*:* Versions 3.11 rc7 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* Versions 7.0 rc1 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* Versions 7.0 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* Versions 7.0 rc3 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* Versions 7.0 rc4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* Versions 7.0 rc5 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.21, 6.19.11, 7.0
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Not affected: 1 product
- Red Hat Enterprise Linux 6
Timeline
- 2026-10-02 Threatist record created from CVE-2026-31450
- 2026-10-03 Alias added: GHSA-fr68-gvh3-4qhv
- 2026-10-16 CISA SSVC decision points changed
- 2026-10-16 Priority changed: LOW → MEDIUM
- 2026-10-19 Weakness changed · CISA ADP
- 2026-10-20 EPSS moved to the below the 50th percentile
References
Patch 8
- https://git.kernel.org/stable/c/2d2b648960147d078b000b9a7494017082024366
- https://git.kernel.org/stable/c/e4325e84727e539c8597bd5b8491349f57f7fb17
- https://git.kernel.org/stable/c/be54c0055407a73b60349c093c8ce621cb8fa232
- https://git.kernel.org/stable/c/a070d5a872ffe0e0fe5c46eda6386140ded39adb
- https://git.kernel.org/stable/c/e76bcb727e4874a2f9d0297f8e3f8eced89b0764
- https://git.kernel.org/stable/c/4855a59e21789c79f003a9b5f4135c95a7495c6b
- https://git.kernel.org/stable/c/33f486987af21531a7b18973d11795ede3da9ddd
- https://git.kernel.org/stable/c/1aec30021edd410b986c156f195f3d23959a9d11
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- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2026-31450 · CVE Program
- CVE-2026-31450 · NVD
- FIRST EPSS
- GHSA-fr68-gvh3-4qhv · GitHub Advisory Database · CC BY 4.0
- CVE-2026-31450 · Red Hat security data · CC BY 4.0
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