From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A1F7D3603ED for ; Tue, 24 Mar 2026 16:55:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774371300; cv=none; b=LgH4RIyPRvAPWPaijrN34MUFxBmzubXrRrdE767Nef8vumNgnnYq0KficZ0ooAmUZNbYkLBq5bRH4dRAxuOEIAtZIqjTdkYFz+U5ZE9zGo+Kfgi6NteboAld3E8vlAu1B3XbdZgPK6+LGiZ9inq8flGkytwqkAcSQ1suxc9RaQ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774371300; c=relaxed/simple; bh=uQJF8WNARBwaAuot29+lUlDiafR2xE1YVZaIfjG3NxA=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=fzCryngheMKvUfXTOnA9bcbfi0UwHsOAKrx/Z7LnzmOoNUnY0uTNVIGd2Y5ixxA/Zm7ZPUyMAvZvK8XK49/w8sLXIxCruJ7UT9/SSDVHf5ZZnM12dDgJ26ZjaN8afY2wLj4x2eSRQ5oeZ9gDIkBZQ51phRkMBGcgqIiWY7Je1FM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IqginkQd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IqginkQd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9EC11C19424; Tue, 24 Mar 2026 16:54:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774371300; bh=uQJF8WNARBwaAuot29+lUlDiafR2xE1YVZaIfjG3NxA=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=IqginkQdbQzZ1lE+jHWXqMZmV567J/TOXdQwkIY1aVNjHqwuZ6iA1Cud7VoqSUtmi Z9uQodftlSAuWeO2TePlOpMhc+ugAT7Dvx4DDcpjwx6cyCOS1cTc5dd+8ZuY3o+O6b jyuuzke3q9DICLFlAXlyvEHjSOyG0m1+vezi2jJLdVws1zgZoY8hwKO2HnapqgKTVt GwBZPIsxvtdkqoW/V/xFvDR3NKsIm04bU1hsmvur3HPu22h/I039vZaHG5ylbFAVK3 fdSjAjySX2Uu3dISeG9Q5lwkJbNS+XZYkKx9d77QSUIYMPg5Lr7r5PKntQN06D8PCY UyKWvshu+xMCA== Message-ID: Subject: Re: [PATCH] NFSD: Fix delegation reference leak in nfsd4_revoke_states From: Jeff Layton To: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-nfs@vger.kernel.org, Chuck Lever Date: Tue, 24 Mar 2026 12:54:57 -0400 In-Reply-To: <20260324151812.85482-1-cel@kernel.org> References: <20260324151812.85482-1-cel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV 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on the stid before calling unhash_delegation_locked(). If > unhash_delegation_locked() returns false (the delegation was already > unhashed by a concurrent path), dp is set to NULL and > revoke_delegation() is skipped, but the extra reference is never > released. Each occurrence permanently pins the stid in memory. The > leaked reference also prevents nfs4_put_stid() from decrementing > cl_admin_revoked, leaving the counter permanently inflated. >=20 > Drop the extra reference in the failure path. >=20 > Fixes: 8dd91e8d31fe ("nfsd: fix race between laundromat and free_stateid"= ) > Signed-off-by: Chuck Lever > --- > fs/nfsd/nfs4state.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) >=20 > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index 6b9c399b89df..0fefae6b0a48 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -1389,7 +1389,8 @@ static void destroy_delegation(struct nfs4_delegati= on *dp) > * stateid or it's called from a laundromat thread (nfsd4_landromat()) t= hat > * determined that this specific state has expired and needs to be revok= ed > * (both mark state with the appropriate stid sc_status mode). It is als= o > - * assumed that a reference was taken on the @dp state. > + * assumed that a reference was taken on the @dp state. This function > + * consumes that reference. > * > * If this function finds that the @dp state is SC_STATUS_FREED it means > * that a FREE_STATEID operation for this stateid has been processed and > @@ -1836,6 +1837,10 @@ void nfsd4_revoke_states(struct nfsd_net *nn, stru= ct super_block *sb) > mutex_unlock(&stp->st_mutex); > break; > case SC_TYPE_DELEG: > + /* Extra reference guards against concurrent > + * FREE_STATEID; revoke_delegation() consumes > + * it, otherwise release it directly. > + */ > refcount_inc(&stid->sc_count); > dp =3D delegstateid(stid); > spin_lock(&state_lock); > @@ -1845,6 +1850,8 @@ void nfsd4_revoke_states(struct nfsd_net *nn, struc= t super_block *sb) > spin_unlock(&state_lock); > if (dp) > revoke_delegation(dp); > + else > + nfs4_put_stid(stid); > break; > case SC_TYPE_LAYOUT: > ls =3D layoutstateid(stid); Good catch! Reviewed-by: Jeff Layton