linux-kernel - Re: [PATCH v2] nfsd: put dl_stid if fail to queue dl

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Message-ID: <173945704787.138332.16372203572251102866.b4-ty@oracle.com>
Date: Thu, 13 Feb 2025 09:31:43 -0500
From: cel@...nel.org
To: jlayton@...nel.org,
	neilb@...e.de,
	okorniev@...hat.com,
	Dai.Ngo@...cle.com,
	tom@...pey.com,
	linux-nfs@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Li Lingfeng <lilingfeng3@...wei.com>
Cc: Chuck Lever <chuck.lever@...cle.com>,
	yukuai1@...weicloud.com,
	houtao1@...wei.com,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	lilingfeng@...weicloud.com
Subject: Re: [PATCH v2] nfsd: put dl_stid if fail to queue dl_recall

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

On Thu, 13 Feb 2025 22:42:20 +0800, Li Lingfeng wrote:
> Before calling nfsd4_run_cb to queue dl_recall to the callback_wq, we
> increment the reference count of dl_stid.
> We expect that after the corresponding work_struct is processed, the
> reference count of dl_stid will be decremented through the callback
> function nfsd4_cb_recall_release.
> However, if the call to nfsd4_run_cb fails, the incremented reference
> count of dl_stid will not be decremented correspondingly, leading to the
> following nfs4_stid leak:
> unreferenced object 0xffff88812067b578 (size 344):
>   comm "nfsd", pid 2761, jiffies 4295044002 (age 5541.241s)
>   hex dump (first 32 bytes):
>     01 00 00 00 6b 6b 6b 6b b8 02 c0 e2 81 88 ff ff  ....kkkk........
>     00 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 ad 4e ad de  .kkkkkkk.....N..
>   backtrace:
>     kmem_cache_alloc+0x4b9/0x700
>     nfsd4_process_open1+0x34/0x300
>     nfsd4_open+0x2d1/0x9d0
>     nfsd4_proc_compound+0x7a2/0xe30
>     nfsd_dispatch+0x241/0x3e0
>     svc_process_common+0x5d3/0xcc0
>     svc_process+0x2a3/0x320
>     nfsd+0x180/0x2e0
>     kthread+0x199/0x1d0
>     ret_from_fork+0x30/0x50
>     ret_from_fork_asm+0x1b/0x30
> unreferenced object 0xffff8881499f4d28 (size 368):
>   comm "nfsd", pid 2761, jiffies 4295044005 (age 5541.239s)
>   hex dump (first 32 bytes):
>     01 00 00 00 00 00 00 00 30 4d 9f 49 81 88 ff ff  ........0M.I....
>     30 4d 9f 49 81 88 ff ff 20 00 00 00 01 00 00 00  0M.I.... .......
>   backtrace:
>     kmem_cache_alloc+0x4b9/0x700
>     nfs4_alloc_stid+0x29/0x210
>     alloc_init_deleg+0x92/0x2e0
>     nfs4_set_delegation+0x284/0xc00
>     nfs4_open_delegation+0x216/0x3f0
>     nfsd4_process_open2+0x2b3/0xee0
>     nfsd4_open+0x770/0x9d0
>     nfsd4_proc_compound+0x7a2/0xe30
>     nfsd_dispatch+0x241/0x3e0
>     svc_process_common+0x5d3/0xcc0
>     svc_process+0x2a3/0x320
>     nfsd+0x180/0x2e0
>     kthread+0x199/0x1d0
>     ret_from_fork+0x30/0x50
>     ret_from_fork_asm+0x1b/0x30
> Fix it by checking the result of nfsd4_run_cb and call nfs4_put_stid if
> fail to queue dl_recall.
> 
> [...]

I replaced the Fixes: tag with Cc: stable.

Applied to nfsd-testing, thanks!

[1/1] nfsd: put dl_stid if fail to queue dl_recall
      commit: d520b70859e0fb6d62ca12eee601a3d6ff4a11b6

--
Chuck Lever