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From
SubjectRe: WARNING: locking bug in nfs_get_client
Date
On Thu, 2019-05-09 at 07:37 -0400, Benjamin Coddington wrote:
> NetApp Security WARNING: This is an external email. Do not click links or open
> attachments unless you recognize the sender and know the content is safe.
>
>
>
>
> I think nfs_get_client and nfs_match_client could use a refactor.. but
> the
> trivial fix is:

Thanks, Ben! I'll go with this fix for now, and we can always clean up the
function later.

Anna

>
> 8<---------------------------------
>
> From 4ef2fc5912c5980890e781f8c0d941330254c100 Mon Sep 17 00:00:00 2001
> Message-Id:
> <4ef2fc5912c5980890e781f8c0d941330254c100.1557401467.git.bcodding@redhat.com>
> From: Benjamin Coddington <bcodding@redhat.com>
> Date: Thu, 9 May 2019 07:25:21 -0400
> Subject: [PATCH] NFS: Fix a double unlock from nfs_match,get_client
>
> Now that nfs_match_client drops the nfs_client_lock, we should be
> careful
> to always return it in the same condition: locked.
>
> Fixes: 950a578c6128 ("NFS: make nfs_match_client killable")
> Reported-by: syzbot+228a82b263b5da91883d@syzkaller.appspotmail.com
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
> ---
> fs/nfs/client.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index 06e8719655f0..da74c4c4a244 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -299,9 +299,9 @@ static struct nfs_client *nfs_match_client(const
> struct nfs_client_initdata *dat
> spin_unlock(&nn->nfs_client_lock);
> error = nfs_wait_client_init_complete(clp);
> nfs_put_client(clp);
> + spin_lock(&nn->nfs_client_lock);
> if (error < 0)
> return ERR_PTR(error);
> - spin_lock(&nn->nfs_client_lock);
> goto again;
> }
>
> --
> 2.20.1
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