CVE-2021-47185 Affecting kernel-debug package, versions <0:5.14.0-503.11.1.el9_5
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-ORACLE9-KERNELDEBUG-8398283
- published20 Nov 2024
- disclosed10 Apr 2024
Introduced: 10 Apr 2024
CVE-2021-47185 (opens in a new tab)How to fix?
Upgrade Oracle:9 kernel-debug to version 0:5.14.0-503.11.1.el9_5 or higher.
This issue was patched in ELSA-2024-9315.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-debug package and not the kernel-debug package as distributed by Oracle.
See How to fix? for Oracle:9 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc
When running ltp testcase(ltp/testcases/kernel/pty/pty04.c) with arm64, there is a soft lockup, which look like this one:
Workqueue: events_unbound flush_to_ldisc Call trace: dump_backtrace+0x0/0x1ec show_stack+0x24/0x30 dump_stack+0xd0/0x128 panic+0x15c/0x374 watchdog_timer_fn+0x2b8/0x304 __run_hrtimer+0x88/0x2c0 __hrtimer_run_queues+0xa4/0x120 hrtimer_interrupt+0xfc/0x270 arch_timer_handler_phys+0x40/0x50 handle_percpu_devid_irq+0x94/0x220 __handle_domain_irq+0x88/0xf0 gic_handle_irq+0x84/0xfc el1_irq+0xc8/0x180 slip_unesc+0x80/0x214 [slip] tty_ldisc_receive_buf+0x64/0x80 tty_port_default_receive_buf+0x50/0x90 flush_to_ldisc+0xbc/0x110 process_one_work+0x1d4/0x4b0 worker_thread+0x180/0x430 kthread+0x11c/0x120
In the testcase pty04, The first process call the write syscall to send data to the pty master. At the same time, the workqueue will do the flush_to_ldisc to pop data in a loop until there is no more data left. When the sender and workqueue running in different core, the sender sends data fastly in full time which will result in workqueue doing work in loop for a long time and occuring softlockup in flush_to_ldisc with kernel configured without preempt. So I add need_resched check and cond_resched in the flush_to_ldisc loop to avoid it.
References
- https://linux.oracle.com/cve/CVE-2021-47185.html
- https://linux.oracle.com/errata/ELSA-2024-3618.html
- https://git.kernel.org/stable/c/0380f643f3a7a61b0845cdc738959c2ad5735d61
- https://git.kernel.org/stable/c/3968ddcf05fb4b9409cd1859feb06a5b0550a1c1
- https://git.kernel.org/stable/c/4c1623651a0936ee197859824cdae6ebbd04d3ed
- https://git.kernel.org/stable/c/4f300f47dbcf9c3d4b2ea76c8554c8f360400725
- https://git.kernel.org/stable/c/5c34486f04700f1ba04907231dce0cc2705c2d7d
- https://git.kernel.org/stable/c/77e9fed33056f2a88eba9dd4d2d5412f0c7d1f41
- https://git.kernel.org/stable/c/b1ffc16ec05ae40d82b6e373322d62e9d6b54fbc
- https://git.kernel.org/stable/c/d491c84df5c469dd9621863b6a770b3428137063