linux-kernel - [BUG] After unloading the nfsd module, a use-after-free occurred due to Objects remaining on __kmem_cache

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Message-ID: <CAGfirffSOjQtJ=FhZ1bhmqDMtdm2UAgvo9TdJNY5hU4KJXQ+pw@mail.gmail.com>
Date: Sun, 12 Oct 2025 05:19:47 +0900
From: 김강민 <km.kim1503@...il.com>
To: chuck.lever@...cle.com, jlayton@...nel.org
Cc: neil@...wn.name, okorniev@...hat.com, Dai.Ngo@...cle.com, tom@...pey.com, 
	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller@...glegroups.com
Subject: [BUG] After unloading the nfsd module, a use-after-free occurred due
 to Objects remaining on __kmem_cache_shutdown().

Dear Linux kernel developers and maintainers,

Hello,
This bug was discovered through syzkaller.

Kernel driver involved: nfsd

Version detected by syzkaller:
- Commit version: cd5a0afbdf8033dc83786315d63f8b325bdba2fd

Details
If the test driver is forcibly unloaded, objects remain in memory,
which can later lead to issues such as use-after-free.
Additionally, This issue can be easily reproduced with the following command.
$ sudo rmmod -f nfsd
Note: Since the nfsd service is running internally with open ports and
mounted shares, it may affect this issue. Therefore, the boot log is
attached as a file.

Please let me know if any further information is required.

Best Regards,
GangMin Kim.

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