CVE-2021-47527 Affecting kernel-rt-debuginfo package, versions <0:4.18.0-553.22.1.rt7.363.el8_10


Severity

Recommended
high

Based on Rocky Linux security rating.

Threat Intelligence

EPSS
0.04% (13th percentile)

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  • Snyk IDSNYK-ROCKY8-KERNELRTDEBUGINFO-8134031
  • published1 Oct 2024
  • disclosed24 May 2024

Introduced: 24 May 2024

CVE-2021-47527  (opens in a new tab)

How to fix?

Upgrade Rocky-Linux:8 kernel-rt-debuginfo to version 0:4.18.0-553.22.1.rt7.363.el8_10 or higher.
This issue was patched in RLSA-2024:7001.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-debuginfo package and not the kernel-rt-debuginfo package as distributed by Rocky-Linux. See How to fix? for Rocky-Linux:8 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

serial: core: fix transmit-buffer reset and memleak

Commit 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") converted serial core to use tty_port_close() but failed to notice that the transmit buffer still needs to be freed on final close.

Not freeing the transmit buffer means that the buffer is no longer cleared on next open so that any ioctl() waiting for the buffer to drain might wait indefinitely (e.g. on termios changes) or that stale data can end up being transmitted in case tx is restarted.

Furthermore, the buffer of any port that has been opened would leak on driver unbind.

Note that the port lock is held when clearing the buffer pointer due to the ldisc race worked around by commit a5ba1d95e46e ("uart: fix race between uart_put_char() and uart_shutdown()").

Also note that the tty-port shutdown() callback is not called for console ports so it is not strictly necessary to free the buffer page after releasing the lock (cf. d72402145ace ("tty/serial: do not free trasnmit buffer page under port lock")).

CVSS Scores

version 3.1