netdev - [Bug] "general protection fault in txopt

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Message-ID: <CAP=Rh=Pi1UcML+85_V6tvhG8oVm6LVc0LoudTyA5_E0ryHcGNA@mail.gmail.com>
Date: Thu, 22 May 2025 22:49:00 +0800
From: John <john.cs.hey@...il.com>
To: "David S. Miller" <davem@...emloft.net>, David Ahern <dsahern@...nel.org>
Cc: Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: [Bug] "general protection fault in txopt_get" in Linux kernel v6.12

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 v6.12.

Git Commit: adc218676eef25575469234709c2d87185ca223a (tag: v6.12)

Bug Location: 0010:txopt_get+0xbc/0x440 include/net/ipv6.h:390

Bug report: https://hastebin.com/share/ruwexefulo.yaml

Complete log: https://hastebin.com/share/inequmeyef.perl

Entire kernel config: https://hastebin.com/share/agatonohuy.ini

Root Cause Analysis:
A malformed netlink message with invalid CALIPSO attributes triggered
a general protection fault via a NULL pointer dereference in the
txopt_get() function (include/net/ipv6.h:390).
The fault occurs because the socket passed into calipso_sock_setattr()
is not guaranteed to be a valid IPv6 socket with properly initialized
transmit options.
The bug demonstrates missing validation of socket type and per-socket
IPv6 metadata in the NetLabel CALIPSO code path. Fixing this requires
enforcing socket type checks and guarding against null dereference in
txopt_get() and its callers.

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,
John