CVE-2021-47280
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…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.18%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.0 HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.18% probability · 8th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-367, CWE-416
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/17dab9326ff263c62dab1dbac4492e2938a049e4Patch
- https://git.kernel.org/stable/c/491d52e0078860b33b6c14f0a7ac74ca1b603bd6Patch
- https://git.kernel.org/stable/c/7d233ba700ceb593905ea82b42dadb4ec8ef85e9Patch
- https://git.kernel.org/stable/c/b246b4c70c1250e7814f409b243000f9c0bf79a3Patch
- https://git.kernel.org/stable/c/b436acd1cf7fac0ba987abd22955d98025c80c2bPatch
- https://git.kernel.org/stable/c/f773f8cccac13c7e7bbd9182e7996c727742488ePatch
- https://git.kernel.org/stable/c/17dab9326ff263c62dab1dbac4492e2938a049e4Patch
- https://git.kernel.org/stable/c/491d52e0078860b33b6c14f0a7ac74ca1b603bd6Patch
- https://git.kernel.org/stable/c/7d233ba700ceb593905ea82b42dadb4ec8ef85e9Patch
- https://git.kernel.org/stable/c/b246b4c70c1250e7814f409b243000f9c0bf79a3Patch
- https://git.kernel.org/stable/c/b436acd1cf7fac0ba987abd22955d98025c80c2bPatch
- https://git.kernel.org/stable/c/f773f8cccac13c7e7bbd9182e7996c727742488ePatch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.