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CVE-2021-47185— tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于flush_to_ldisk中存在软锁定问题。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.18% · P7

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 81de916f19cf5f1437c0b9ed817364f0f7c81961< 0380f643f3a7a61b0845cdc738959c2ad5735d61 affected
81de916f19cf5f1437c0b9ed817364f0f7c81961< b1ffc16ec05ae40d82b6e373322d62e9d6b54fbc affected
81de916f19cf5f1437c0b9ed817364f0f7c81961< 4c1623651a0936ee197859824cdae6ebbd04d3ed affected
81de916f19cf5f1437c0b9ed817364f0f7c81961< 4f300f47dbcf9c3d4b2ea76c8554c8f360400725 affected
81de916f19cf5f1437c0b9ed817364f0f7c81961< d491c84df5c469dd9621863b6a770b3428137063 affected
81de916f19cf5f1437c0b9ed817364f0f7c81961< 77e9fed33056f2a88eba9dd4d2d5412f0c7d1f41 affected
81de916f19cf5f1437c0b9ed817364f0f7c81961< 5c34486f04700f1ba04907231dce0cc2705c2d7d affected
81de916f19cf5f1437c0b9ed817364f0f7c81961< 3968ddcf05fb4b9409cd1859feb06a5b0550a1c1 affected
… +10 more rows
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I. Basic Information for CVE-2021-47185

Vulnerability Information
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Vulnerability Title
tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于flush_to_ldisk中存在软锁定问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 81de916f19cf5f1437c0b9ed817364f0f7c81961 ~ 0380f643f3a7a61b0845cdc738959c2ad5735d61 -
Linux Linux 3.0 -

II. Public POCs for CVE-2021-47185

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III. Intelligence Information for CVE-2021-47185

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Patches & Fixes for CVE-2021-47185 (1)

Other References for CVE-2021-47185 (7)

Same Patch Batch · Linux · 2024-04-10 · 39 CVEs total

CVE-2021-47215 9.8 CRITICAL net/mlx5e: kTLS, Fix crash in RX resync flow
CVE-2021-47203 8.8 HIGH scsi: lpfc: Fix list_add() corruption in lpfc_drain_txq()
CVE-2021-47183 8.8 HIGH scsi: lpfc: Fix link down processing to address NULL pointer dereference
CVE-2021-47184 8.8 HIGH i40e: Fix NULL ptr dereference on VSI filter sync
CVE-2021-47189 7.8 HIGH btrfs: fix memory ordering between normal and ordered work functions
CVE-2021-47197 7.8 HIGH net/mlx5e: nullify cq->dbg pointer in mlx5_debug_cq_remove()
CVE-2021-47196 7.8 HIGH RDMA/core: Set send and receive CQ before forwarding to the driver
CVE-2021-47209 7.8 HIGH sched/fair: Prevent dead task groups from regaining cfs_rq's
CVE-2021-47194 7.8 HIGH cfg80211: call cfg80211_stop_ap when switch from P2P_GO type
CVE-2024-26815 7.8 HIGH net/sched: taprio: proper TCA_TAPRIO_TC_ENTRY_INDEX check
CVE-2021-47200 7.8 HIGH drm/prime: Fix use after free in mmap with drm_gem_ttm_mmap
CVE-2021-47201 7.8 HIGH iavf: free q_vectors before queues in iavf_disable_vf
CVE-2021-47188 7.8 HIGH scsi: ufs: core: Improve SCSI abort handling
CVE-2021-47191 7.1 HIGH scsi: scsi_debug: Fix out-of-bound read in resp_readcap16()
CVE-2021-47219 7.1 HIGH scsi: scsi_debug: Fix out-of-bound read in resp_report_tgtpgs()
CVE-2021-47206 usb: host: ohci-tmio: check return value after calling platform_get_resource()
CVE-2021-47207 ALSA: gus: fix null pointer dereference on pointer block
CVE-2021-47199 net/mlx5e: CT, Fix multiple allocations and memleak of mod acts
CVE-2021-47210 usb: typec: tipd: Remove WARN_ON in tps6598x_block_read
CVE-2021-47211 ALSA: usb-audio: fix null pointer dereference on pointer cs_desc

Showing top 20 of 39 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2021-47185

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