[Bug] soft lockup in __sk_free in Linux kernel v6.13
From: Luka <hidden>
Date: 2025-07-08 07:58:21
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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