ext4: don't BUG if someone dirty pages without asking ext4 first
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 4 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-617.
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: don't BUG if someone dirty pages without asking ext4 first [un]pin_user_pages_remote is dirtying pages without properly warning the file system in advance. A related race was noted by Jan Kara in 2018[1]; however, more recently instead of it being a very hard-to-hit race, it could be reliably triggered by process_vm_writev(2) which was discovered by Syzbot[2]. This is technically a bug in mm/gup.c, but arguably ext4 is fragile in that if some other kernel subsystem dirty pages without properly notifying the file system using page_mkwrite(), ext4 will BUG, while other file systems will not BUG (although data will still be lost). So instead of crashing with a BUG, issue a warning (since there may be potential data loss) and just mark the page as clean to avoid unprivileged denial of service attacks until the problem can be properly fixed. More discussion and background can be found in the thread starting at [2]. [1] https://lore.kernel.org/linux-mm/[email protected] [2] https://lore.kernel.org/r/[email protected]
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
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 | 2.6.37 and later | 4.9.311, 4.14.276, 4.19.238, 5.4.189, 5.10.110, 5.15.33, 5.16.19, 5.17.2, 5.18 | Patch available | CNA |
- Linux VendorLinux Affected 2.6.37 and later Fixed in 4.9.311, 4.14.276, 4.19.238, 5.4.189, 5.10.110, 5.15.33, 5.16.19, 5.17.2, 5.18 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | before 4.9.311; 4.10 to before 4.14.276; 4.15 to before 4.19.238; 4.20 to before 5.4.189; 5.5 to before 5.10.110; 5.11 to before 5.15.33; 5.16 to before 5.16.19; 5.17 to before 5.17.2 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions before 4.9.311; 4.10 to before 4.14.276; 4.15 to before 4.19.238; 4.20 to before 5.4.189; 5.5 to before 5.10.110; 5.11 to before 5.15.33; 5.16 to before 5.16.19; 5.17 to before 5.17.2 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 4.9.311, 4.14.276, 4.19.238, 5.4.189, 5.10.110, 5.15.33, 5.16.19, 5.17.2, 5.18
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 8 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
Not affected: 1 product
- Red Hat Enterprise Linux 10
Timeline
- 2026-10-02 Threatist record created from CVE-2022-49171
- 2026-10-03 Alias added: GHSA-qgfx-vv83-vj4g
- 2026-11-05 CISA SSVC decision points changed
References
Patch 9
- https://git.kernel.org/stable/c/5db60e76edf5680ff1f3a7221036fc44b308f146
- https://git.kernel.org/stable/c/d666dfaa571465a19f014534a214c255ea33f301
- https://git.kernel.org/stable/c/0d3a6926f7e8be3c897fa46216ce13b119a9f56a
- https://git.kernel.org/stable/c/5a016c053f426a73752c3b41b60b497b58694d48
- https://git.kernel.org/stable/c/330d0e44fc5a47c27df958ecdd4693a3cb1d8b81
- https://git.kernel.org/stable/c/a0856764dc1276ad2dc7891288c2e9246bf11a37
- https://git.kernel.org/stable/c/343117559ef41e992e326f7a92da1a8f254dfa8c
- https://git.kernel.org/stable/c/677c9d30e8487bee6c8e3b034070319d98f6e203
- https://git.kernel.org/stable/c/cc5095747edfb054ca2068d01af20be3fcc3634f
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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-2022-49171 · CVE Program
- CVE-2022-49171 · NVD
- FIRST EPSS
- GHSA-qgfx-vv83-vj4g · GitHub Advisory Database · CC BY 4.0
- CVE-2022-49171 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences