drm: Fix use-after-free read in drm_getunique()
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 3 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.
Summary
In the Linux kernel, the following vulnerability has been resolved: drm: Fix use-after-free read in drm_getunique() There is a time-of-check-to-time-of-use error in drm_getunique() due to retrieving file_priv->master prior to locking the device's master mutex. An example can be seen in the crash report of the use-after-free error found by Syzbot: https://syzkaller.appspot.com/bug?id=148d2f1dfac64af52ffd27b661981a540724f803 In the report, the master pointer was used after being freed. This is because another process had acquired the device's master mutex in drm_setmaster_ioctl(), then overwrote fpriv->master in drm_new_set_master(). The old value of fpriv->master was subsequently freed before the mutex was unlocked. To fix this, we lock the device's master mutex before retrieving the pointer from from fpriv->master. This patch passes the Syzbot reproducer test.
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 | 4.11 and later | 4.14.237, 4.19.195, 5.4.126, 5.10.44, 5.12.11, 5.13 | Patch available | CNA |
- Linux VendorLinux Affected 4.11 and later Fixed in 4.14.237, 4.19.195, 5.4.126, 5.10.44, 5.12.11, 5.13 Patch available CNA
CPE configurations NVD · 6
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | before 4.14.237; 4.15 to before 4.19.195; 4.20 to before 5.4.126; 5.5 to before 5.10.44; 5.11 to before 5.12.11 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:* | 5.13 rc1 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.13:rc2:*:*:*:*:*:* | 5.13 rc2 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.13:rc3:*:*:*:*:*:* | 5.13 rc3 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.13:rc4:*:*:*:*:*:* | 5.13 rc4 | Vulnerable | Linux |
| cpe:2.3:o:linux:linux_kernel:5.13:rc5:*:*:*:*:*:* | 5.13 rc5 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions before 4.14.237; 4.15 to before 4.19.195; 4.20 to before 5.4.126; 5.5 to before 5.10.44; 5.11 to before 5.12.11 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:* Versions 5.13 rc1 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.13:rc2:*:*:*:*:*:* Versions 5.13 rc2 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.13:rc3:*:*:*:*:*:* Versions 5.13 rc3 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.13:rc4:*:*:*:*:*:* Versions 5.13 rc4 Vulnerable ·Linux
- cpe:2.3:o:linux:linux_kernel:5.13:rc5:*:*:*:*:*:* Versions 5.13 rc5 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 4.14.237, 4.19.195, 5.4.126, 5.10.44, 5.12.11, 5.13
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 yet |
Not affected: 1 product
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2021-47280
- 2026-10-03 Alias added: GHSA-rcjv-j3v6-r6cv
References
Patch 6
- https://git.kernel.org/stable/c/17dab9326ff263c62dab1dbac4492e2938a049e4
- https://git.kernel.org/stable/c/7d233ba700ceb593905ea82b42dadb4ec8ef85e9
- https://git.kernel.org/stable/c/b246b4c70c1250e7814f409b243000f9c0bf79a3
- https://git.kernel.org/stable/c/491d52e0078860b33b6c14f0a7ac74ca1b603bd6
- https://git.kernel.org/stable/c/f773f8cccac13c7e7bbd9182e7996c727742488e
- https://git.kernel.org/stable/c/b436acd1cf7fac0ba987abd22955d98025c80c2b
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Sources
- CVE-2021-47280 · CVE Program
- CVE-2021-47280 · NVD
- FIRST EPSS
- GHSA-rcjv-j3v6-r6cv · GitHub Advisory Database · CC BY 4.0
- CVE-2021-47280 · Red Hat security data · CC BY 4.0
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