CVE-2021-47185
Description
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Vendor advisory: alma — https://errata.almalinux.org/8/ALSA-2024-3627.html
Vendor advisory: alma — https://access.redhat.com/errata/RHSA-2024:3627
Vendor advisory: alma — https://errata.almalinux.org/8/ALSA-2024-3618.html
Vendor advisory: alma — https://bugzilla.redhat.com/2278537
Vendor advisory: alma — https://bugzilla.redhat.com/2278431
Vendor advisory: alma — https://bugzilla.redhat.com/2278417
Vendor advisory: alma — https://bugzilla.redhat.com/2278409
Vendor advisory: alma — https://bugzilla.redhat.com/2278398
Vendor advisory: alma — https://bugzilla.redhat.com/2278356
Vendor advisory: alma — https://bugzilla.redhat.com/2278314
Vendor advisory: alma — https://bugzilla.redhat.com/2278268
Vendor advisory: alma — https://bugzilla.redhat.com/2278240
Vendor advisory: alma — https://bugzilla.redhat.com/2278237
Vendor advisory: alma — https://bugzilla.redhat.com/2278169
Vendor advisory: alma — https://bugzilla.redhat.com/2275777
Vendor advisory: alma — https://bugzilla.redhat.com/2275707
Vendor advisory: alma — https://bugzilla.redhat.com/2275666
Vendor advisory: alma — https://bugzilla.redhat.com/2275655
Vendor advisory: alma — https://bugzilla.redhat.com/2275645
Vendor advisory: alma — https://bugzilla.redhat.com/2274624
Vendor advisory: alma — https://bugzilla.redhat.com/2273262
Vendor advisory: alma — https://bugzilla.redhat.com/2273260
Vendor advisory: alma — https://bugzilla.redhat.com/2273223
Vendor advisory: alma — https://bugzilla.redhat.com/2273094
Vendor advisory: alma — https://bugzilla.redhat.com/2273092
Vendor advisory: alma — https://bugzilla.redhat.com/2272791
Vendor advisory: alma — https://bugzilla.redhat.com/2272780
Vendor advisory: alma — https://bugzilla.redhat.com/2271476
Vendor advisory: alma — https://bugzilla.redhat.com/2271469
Vendor advisory: alma — https://bugzilla.redhat.com/2270881
Vendor advisory: alma — https://bugzilla.redhat.com/2270879
Vendor advisory: alma — https://bugzilla.redhat.com/2270080
Vendor advisory: alma — https://bugzilla.redhat.com/2269856
Vendor advisory: alma — https://bugzilla.redhat.com/2269213
Vendor advisory: alma — https://bugzilla.redhat.com/2268317
Vendor advisory: alma — https://bugzilla.redhat.com/2268315
Vendor advisory: alma — https://bugzilla.redhat.com/2268309
Vendor advisory: alma — https://bugzilla.redhat.com/2268293
Vendor advisory: alma — https://bugzilla.redhat.com/2268291
Vendor advisory: alma — https://bugzilla.redhat.com/2267804
Vendor advisory: alma — https://bugzilla.redhat.com/2267797
Vendor advisory: alma — https://bugzilla.redhat.com/2267789
Vendor advisory: alma — https://bugzilla.redhat.com/2267758
Vendor advisory: alma — https://bugzilla.redhat.com/2267724
Vendor advisory: alma — https://bugzilla.redhat.com/2267705
Vendor advisory: alma — https://bugzilla.redhat.com/2267509
Vendor advisory: alma — https://bugzilla.redhat.com/2267355
Vendor advisory: alma — https://bugzilla.redhat.com/2267185
Vendor advisory: alma — https://bugzilla.redhat.com/2267038
Vendor advisory: alma — https://bugzilla.redhat.com/2266841
Vendor advisory: alma — https://bugzilla.redhat.com/2266746
Vendor advisory: alma — https://bugzilla.redhat.com/2266446
Vendor advisory: alma — https://bugzilla.redhat.com/2266296
Vendor advisory: alma — https://bugzilla.redhat.com/2265833
Vendor advisory: alma — https://bugzilla.redhat.com/2265654
Vendor advisory: alma — https://bugzilla.redhat.com/2265646
Vendor advisory: alma — https://bugzilla.redhat.com/2265271
Vendor advisory: alma — https://bugzilla.redhat.com/2263875
Vendor advisory: alma — https://bugzilla.redhat.com/2257406
Vendor advisory: alma — https://bugzilla.redhat.com/2250843
Vendor advisory: alma — https://access.redhat.com/errata/RHSA-2024:3618
Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2021-47185
Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2021-47185.html
Vendor advisory: rocky — https://errata.rockylinux.org/RLSA-2024:3618
Vendor advisory: rocky — https://errata.rockylinux.org/RLSA-2024:3627
Vendor advisory: redhat — https://access.redhat.com/errata/RHSA-2024:9315
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| rhel | 9 | fixed | |
| rocky | 8 | fixed | |
| sles | affected | | |
| debian | bookworm | fixed | 5.15.5-1 |
| debian | bullseye | fixed | 5.10.84-1 |
| debian | forky | fixed | 5.15.5-1 |
| debian | sid | fixed | 5.15.5-1 |
| debian | trixie | fixed | 5.15.5-1 |
References
- https://access.redhat.com/errata/RHSA-2024:9315
- https://errata.rockylinux.org/RLSA-2024:3627
- https://errata.rockylinux.org/RLSA-2024:3618
- https://www.suse.com/security/cve/CVE-2021-47185.html
- https://security-tracker.debian.org/tracker/CVE-2021-47185
- https://access.redhat.com/errata/RHSA-2024:3618
- https://bugzilla.redhat.com/2250843
- https://bugzilla.redhat.com/2257406
- https://bugzilla.redhat.com/2263875
- https://bugzilla.redhat.com/2265271
- https://bugzilla.redhat.com/2265646
- https://bugzilla.redhat.com/2265654
- https://bugzilla.redhat.com/2265833
- https://bugzilla.redhat.com/2266296
- https://bugzilla.redhat.com/2266446
- https://bugzilla.redhat.com/2266746
- https://bugzilla.redhat.com/2266841
- https://bugzilla.redhat.com/2267038
- https://bugzilla.redhat.com/2267185
- https://bugzilla.redhat.com/2267355
- https://bugzilla.redhat.com/2267509
- https://bugzilla.redhat.com/2267705
- https://bugzilla.redhat.com/2267724
- https://bugzilla.redhat.com/2267758
- https://bugzilla.redhat.com/2267789
Verify integrity in audit chain (admin only). AS-IS.