# CVE-2025-39782

## Summary

- **CVE ID:** CVE-2025-39782
- **Severity:** MEDIUM
- **CVSS Score:** 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2025
- **Last Modified:** Sep 8, 2026

## Description

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

jbd2: prevent softlockup in jbd2_log_do_checkpoint()

Both jbd2_log_do_checkpoint() and jbd2_journal_shrink_checkpoint_list()
periodically release j_list_lock after processing a batch of buffers to
avoid long hold times on the j_list_lock. However, since both functions
contend for j_list_lock, the combined time spent waiting and processing
can be significant.

jbd2_journal_shrink_checkpoint_list() explicitly calls cond_resched() when
need_resched() is true to avoid softlockups during prolonged operations.
But jbd2_log_do_checkpoint() only exits its loop when need_resched() is
true, relying on potentially sleeping functions like __flush_batch() or
wait_on_buffer() to trigger rescheduling. If those functions do not sleep,
the kernel may hit a softlockup.

watchdog: BUG: soft lockup - CPU#3 stuck for 156s! [kworker/u129:2:373]
CPU: 3 PID: 373 Comm: kworker/u129:2 Kdump: loaded Not tainted 6.6.0+ #10
Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.27 06/13/2017
Workqueue: writeback wb_workfn (flush-7:2)
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : native_queued_spin_lock_slowpath+0x358/0x418
lr : jbd2_log_do_checkpoint+0x31c/0x438 [jbd2]
Call trace:
 native_queued_spin_lock_slowpath+0x358/0x418
 jbd2_log_do_checkpoint+0x31c/0x438 [jbd2]
 __jbd2_log_wait_for_space+0xfc/0x2f8 [jbd2]
 add_transaction_credits+0x3bc/0x418 [jbd2]
 start_this_handle+0xf8/0x560 [jbd2]
 jbd2__journal_start+0x118/0x228 [jbd2]
 __ext4_journal_start_sb+0x110/0x188 [ext4]
 ext4_do_writepages+0x3dc/0x740 [ext4]
 ext4_writepages+0xa4/0x190 [ext4]
 do_writepages+0x94/0x228
 __writeback_single_inode+0x48/0x318
 writeback_sb_inodes+0x204/0x590
 __writeback_inodes_wb+0x54/0xf8
 wb_writeback+0x2cc/0x3d8
 wb_do_writeback+0x2e0/0x2f8
 wb_workfn+0x80/0x2a8
 process_one_work+0x178/0x3e8
 worker_thread+0x234/0x3b8
 kthread+0xf0/0x108
 ret_from_fork+0x10/0x20

So explicitly call cond_resched() in jbd2_log_do_checkpoint() to avoid
softlockup.

## Affected Products

- Linux — Linux (f93ea411b73594f7d144855fd34278bcf34a9afc)
- Linux — Linux (2.6.16)
- Linux — Linux (0)
- Linux — Linux (5.4.297)
- Linux — Linux (5.10.241)
- Linux — Linux (5.15.190)
- Linux — Linux (6.1.149)
- Linux — Linux (6.6.103)
- Linux — Linux (6.12.44)
- Linux — Linux (6.16.4)
- Linux — Linux (6.17)

## References

- [CNA](https://git.kernel.org/stable/c/f683d611518d30334813eecf9a8c687453e2800e)
- [CNA](https://git.kernel.org/stable/c/f7ee8fd689e6d534f9fd2494b9266f7998082e65)
- [CNA](https://git.kernel.org/stable/c/84ff98c1ea19acd3f9389e4bb6061364e943f85e)
- [CNA](https://git.kernel.org/stable/c/26cb9aad94cb1811d8fae115594cc71fa3d91ab0)
- [CNA](https://git.kernel.org/stable/c/41f40038de62e8306897cf6840791b268996432a)
- [CNA](https://git.kernel.org/stable/c/429d50cbaff45090d52a1ea850d5de8c14881ee7)
- [CNA](https://git.kernel.org/stable/c/3faac5e1d14c63260fd1bf789d96bde3ab3d9e54)
- [CNA](https://git.kernel.org/stable/c/9d98cf4632258720f18265a058e62fde120c0151)
- [CVE](https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html)
- [CVE](https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-032379.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-019113.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.12%
- **EPSS Percentile:** 2.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._