[Bug] soft lockup in __sk_free in Linux kernel v6.13
From: Luka
Date: Tue Jul 08 2025 - 03:59:08 EST
Dear Linux Kernel Maintainers,
I hope this message finds you well.
I am writing to report a potential vulnerability I encountered during
testing of the Linux Kernel version v6.13.
Git Commit: ffd294d346d185b70e28b1a28abe367bbfe53c04 (tag: v6.13)
Bug Location: __sk_free+0x1a9/0x4b0 net/core/sock.c:2322
Bug report: https://pastebin.com/0T4EFSse
Entire kernel config: https://pastebin.com/LepsHYGb
Root Cause Analysis:
A soft lockup is triggered during socket deallocation due to prolonged
execution in __sk_free(), where the destruction of socket-related
resources under heavy task context and scheduler pressure leads to
excessive CPU time consumption without preemption, ultimately stalling
the CPU and activating the watchdog.
At present, I have not yet obtained a minimal reproducer for this
issue. However, I am actively working on reproducing it, and I will
promptly share any additional findings or a working reproducer as soon
as it becomes available.
Thank you very much for your time and attention to this matter. I
truly appreciate the efforts of the Linux kernel community.
Best regards,
Luka