Re: [Bug] task hung in rtnl_newlink in Linux kernel v6.12

[Kuniyuki Iwashima <kuni1840@gmail.com>]

From: Luka <luka.2016.cs@gmail.com>
Date: Wed, 4 Jun 2025 12:18:55 +0800
> Dear Kernel Maintainers,
> 
> I am writing to report a potential vulnerability identified in the
> upstream Linux Kernel version v6.12, corresponding to the following
> commit in the mainline repository:
> 
> Git Commit:  adc218676eef25575469234709c2d87185ca223a (tag: v6.12)

Please run syzkaller on the latest upstream or at least the latest LTS
release.

> 
> This issue was discovered during the testing of the Android 16 AOSP
> kernel, which is based on Linux kernel version 6.12, specifically from
> the AOSP kernel branch:
> 
> AOSP kernel branch: android16-6.12
> Manifest path: kernel/common.git
> Source URL:  https://android.googlesource.com/kernel/common/+/refs/heads/android16-6.12
> 
> Although this kernel branch is used in Android 16 development, its
> base is aligned with the upstream Linux v6.12 release. I observed this
> issue while conducting stability and fuzzing tests on the Android 16
> platform and identified that the root cause lies in the upstream
> codebase.
> 
> 
> Bug Location: rtnl_newlink+0x64c/0x12f4 net/core/rtnetlink.c:3772

You can find a bunch of similar reports in the mailing list or the
syzbot dashboard, where too many threads waiting for the same global
mutex, e.g.

https://lore.kernel.org/netdev/tencent_A3FB41E607B2126D163C5D4C87DC196E0707@qq.com/

When you don't have a repro, please make sure there is no duplicate
report before posting.

Thanks

> 
> Bug Report: https://hastebin.com/share/omisagagir.bash
> 
> Entire Log: https://hastebin.com/share/cetuxoduko.perl
> 
> 
> Thank you very much for your time and attention. I sincerely apologize
> that I am currently unable to provide a reproducer for this issue.
> However, I am actively working on reproducing the problem, and I will
> make sure to share any findings or reproducing steps with you as soon
> as they are available.
> 
> I greatly appreciate your efforts in maintaining the Linux kernel and
> your attention to this matter.
>