cbcvebase.
CVE-2021-47185
published 2024-04-10

CVE-2021-47185: In the Linux kernel, the following vulnerability has been resolved: tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc When running ltp…

PriorityP415medium4.4CVSS 3.1
AVLACLPRHUINSUCNINAH
EPSS
0.18%
7.6th percentile
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.

Affected

21 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 5.15.5-1 (bookworm)linux 5.15.5-1 (bookworm)
linuxlinux——
linuxlinux>= 81de916f19cf5f1437c0b9ed817364f0f7c81961 < 0380f643f3a7a61b0845cdc738959c2ad5735d610380f643f3a7a61b0845cdc738959c2ad5735d61
linuxlinux>= 81de916f19cf5f1437c0b9ed817364f0f7c81961 < b1ffc16ec05ae40d82b6e373322d62e9d6b54fbcb1ffc16ec05ae40d82b6e373322d62e9d6b54fbc
linuxlinux>= 81de916f19cf5f1437c0b9ed817364f0f7c81961 < 4c1623651a0936ee197859824cdae6ebbd04d3ed4c1623651a0936ee197859824cdae6ebbd04d3ed
linuxlinux>= 81de916f19cf5f1437c0b9ed817364f0f7c81961 < 4f300f47dbcf9c3d4b2ea76c8554c8f3604007254f300f47dbcf9c3d4b2ea76c8554c8f360400725
linuxlinux>= 81de916f19cf5f1437c0b9ed817364f0f7c81961 < d491c84df5c469dd9621863b6a770b3428137063d491c84df5c469dd9621863b6a770b3428137063
linuxlinux>= 81de916f19cf5f1437c0b9ed817364f0f7c81961 < 77e9fed33056f2a88eba9dd4d2d5412f0c7d1f4177e9fed33056f2a88eba9dd4d2d5412f0c7d1f41
linuxlinux>= 81de916f19cf5f1437c0b9ed817364f0f7c81961 < 5c34486f04700f1ba04907231dce0cc2705c2d7d5c34486f04700f1ba04907231dce0cc2705c2d7d
linuxlinux>= 81de916f19cf5f1437c0b9ed817364f0f7c81961 < 3968ddcf05fb4b9409cd1859feb06a5b0550a1c13968ddcf05fb4b9409cd1859feb06a5b0550a1c1
linuxlinux_kernel< 4.4.2934.4.293
linuxlinux_kernel>= 0 < 5.10.84-15.10.84-1
linuxlinux_kernel>= 0 < 5.15.5-15.15.5-1
linuxlinux_kernel>= 0 < 5.15.5-15.15.5-1
linuxlinux_kernel>= 0 < 5.15.5-15.15.5-1
linuxlinux_kernel>= 4.10 < 4.14.2564.14.256
linuxlinux_kernel>= 4.15 < 4.19.2184.19.218
linuxlinux_kernel>= 4.20 < 5.4.1625.4.162
linuxlinux_kernel>= 4.5 < 4.9.2914.9.291
linuxlinux_kernel>= 5.11 < 5.15.55.15.5
linuxlinux_kernel>= 5.5 < 5.10.825.10.82

CVSS provenance

nvdv3.14.4MEDIUMCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
osv4.4MEDIUM
vendor_debian4.4MEDIUM
vendor_redhat4.4MEDIUM
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.