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.
OS | Version | Architecture | Package | Version | Filename |
---|---|---|---|---|---|
ubuntu | 18.04 | noarch | linux | <Â any | UNKNOWN |
ubuntu | 20.04 | noarch | linux | <Â any | UNKNOWN |
ubuntu | 18.04 | noarch | linux-aws | <Â any | UNKNOWN |
ubuntu | 20.04 | noarch | linux-aws | <Â any | UNKNOWN |
ubuntu | 18.04 | noarch | linux-aws-5.4 | <Â any | UNKNOWN |
ubuntu | 16.04 | noarch | linux-aws-hwe | <Â any | UNKNOWN |
ubuntu | 20.04 | noarch | linux-azure | <Â any | UNKNOWN |
ubuntu | 14.04 | noarch | linux-azure | <Â any | UNKNOWN |
ubuntu | 16.04 | noarch | linux-azure | <Â any | UNKNOWN |
ubuntu | 18.04 | noarch | linux-azure-4.15 | <Â any | UNKNOWN |
git.kernel.org/linus/b436acd1cf7fac0ba987abd22955d98025c80c2b (5.13-rc6)
git.kernel.org/stable/c/17dab9326ff263c62dab1dbac4492e2938a049e4
git.kernel.org/stable/c/491d52e0078860b33b6c14f0a7ac74ca1b603bd6
git.kernel.org/stable/c/7d233ba700ceb593905ea82b42dadb4ec8ef85e9
git.kernel.org/stable/c/b246b4c70c1250e7814f409b243000f9c0bf79a3
git.kernel.org/stable/c/b436acd1cf7fac0ba987abd22955d98025c80c2b
git.kernel.org/stable/c/f773f8cccac13c7e7bbd9182e7996c727742488e
launchpad.net/bugs/cve/CVE-2021-47280
nvd.nist.gov/vuln/detail/CVE-2021-47280
security-tracker.debian.org/tracker/CVE-2021-47280
www.cve.org/CVERecord?id=CVE-2021-47280