linux-kernel - [Bug] soft lockup in xfrm_timer

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Message-ID: <CALm_T+2C9=XT-9R+DyRVhHfADDtsbMxh9u3q1fYKiPHkyo917A@mail.gmail.com>
Date: Tue, 8 Jul 2025 15:43:05 +0800
From: Luka <luka.2016.cs@...il.com>
To: Steffen Klassert <steffen.klassert@...unet.com>, Herbert Xu <herbert@...dor.apana.org.au>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [Bug] soft lockup in xfrm_timer_handler in Linux kernel v6.15

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 v6.15.

Git Commit: 0ff41df1cb268fc69e703a08a57ee14ae967d0ca (tag: v6.15)

Bug Location: xfrm_timer_handler+0x824/0xbb0 net/xfrm/xfrm_state.c:718

Bug report: https://pastebin.com/mSiia4CU

Entire kernel config: https://pastebin.com/jQ30sdLk

Root Cause Analysis:

A soft lockup occurs in the IPsec state expiration handler
xfrm_timer_handler(), caused by excessive execution time during state
notification, likely due to long-running operations in
xfrm_send_state_notify() under high-resolution timer context,
resulting in CPU starvation and scheduling failure on the softirq
path.

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