linux-kernel - Re: [PATCH] nfsd: Initialize ssc before laundromat

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Message-ID: <174465166461.41191.18027879549273675051.b4-ty@oracle.com>
Date: Mon, 14 Apr 2025 13:29:03 -0400
From: cel@...nel.org
To: jlayton@...nel.org,
	neil@...wn.name,
	okorniev@...hat.com,
	Dai.Ngo@...cle.com,
	tom@...pey.com,
	Li Lingfeng <lilingfeng3@...wei.com>
Cc: Chuck Lever <chuck.lever@...cle.com>,
	linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	yukuai1@...weicloud.com,
	houtao1@...wei.com,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	lilingfeng@...weicloud.com
Subject: Re: [PATCH] nfsd: Initialize ssc before laundromat_work to prevent NULL dereference

From: Chuck Lever <chuck.lever@...cle.com>

On Mon, 14 Apr 2025 22:38:52 +0800, Li Lingfeng wrote:
> In nfs4_state_start_net(), laundromat_work may access nfsd_ssc through
> nfs4_laundromat -> nfsd4_ssc_expire_umount. If nfsd_ssc isn't initialized,
> this can cause NULL pointer dereference.
> 
> Normally the delayed start of laundromat_work allows sufficient time for
> nfsd_ssc initialization to complete. However, when the kernel waits too
> long for userspace responses (e.g. in nfs4_state_start_net ->
> nfsd4_end_grace -> nfsd4_record_grace_done -> nfsd4_cld_grace_done ->
> cld_pipe_upcall -> __cld_pipe_upcall -> wait_for_completion path), the
> delayed work may start before nfsd_ssc initialization finishes.
> 
> [...]

Applied to nfsd-testing, thanks!

[1/1] nfsd: Initialize ssc before laundromat_work to prevent NULL dereference
      commit: 05d68df60b9af7765c38073ff117169aa5f52310

--
Chuck Lever