From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 169524A3F19 for ; Sat, 5 Sep 2026 16:50:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788627052; cv=none; b=D3yXIeAaHCTzCN4b/2sPdvGinK/bfxsDUyG8PEf1WE53f9K2JEdxTwX17yrYe63UFPW3VO6hhJvtnLujYeWAe8gL+i/BOBK8ox02fAHLGKBDRrUvTWuUrt4fBurcVhEuqKhl/KAWA3/LauFmcXs2y6oQqMkGcJckaXvx3iYkcEI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788627052; c=relaxed/simple; bh=Bi7uGM4Mau65oeParTbOUtt2bsD05UCg5o6VYJILrMc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OZz3BvBJ6mTbLa6Qhz0RwCsCHneqiQhuvBJlDrl+nXCClF5U9VuRDEFAfe8n2ZRej6L/3Rrdixi/o0a/ly6KW/bpxenaHIUTnuwQyNce4/ZnZzVpuq+0lctqT+XYBslnxKmNgPbeGMGejo9+eeHwHl6LWlJn5LNgZAoPCdayX4k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PT3Jp4xI; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PT3Jp4xI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5FEC31F00A3A; Sat, 5 Sep 2026 16:50:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788627051; bh=qsEXmR8tgPYw/vubk+K7oduLwLlET0/WSKuriEN8K2A=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PT3Jp4xIDJL7Jedn8V9CZYdWvV1OBl+qZ1UhAZorOmIIEjJ/414gWU8lSTldmd9Pk TBghLVf/rNQhpSlaWC6jBDfzAKvlfD4e0qU+V5h5bQtOjg5mAe8cPwoCt2Nt3QXtXJ 092HzU72uFuEtkbojXEaNvu3AfItpBD4Dq/pphHReO5o1etzJMehhS/gsPUc+AAUwr D3fzPKwRyH186NPQt/uH/9vvyfttBp6PL4Aztp/BssQ0QisDMWdbt6lzj7LgtoK0MV S4O86ehTtW6XOtMXGbAM5H0LOkrLMcTpgdn6Kn67Hoze0dXjhPXQ4uYHh+mcCKq7wS FXa2HOQxocI+Q== From: Sasha Levin To: stable@vger.kernel.org Cc: Jeff Layton , Chris Mason , Chuck Lever , Sasha Levin Subject: [PATCH 5.10.y] nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke Date: Sat, 5 Sep 2026 12:50:48 -0400 Message-ID: <20260905165048.471453-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090306-ducktail-chant-83eb@gregkh> References: <2026090306-ducktail-chant-83eb@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jeff Layton [ Upstream commit ca94ba36172046be6a694a7986f6931e47ed4d51 ] nfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding fi_lock when the parent stateid is a delegation. A concurrent delegation revoke via the laundromat can clear fi_deleg_file under fi_lock, causing nfsd_file_get() to return NULL and triggering the BUG_ON. This race is client-reachable: two NFS clients can trigger it by having one hold a delegation while another opens the same file to force a recall. When the first client doesn't respond to the recall, the laundromat revokes it. A concurrent LAYOUTGET from any client using the delegation stateid hits the race window. Fix this by taking fi_lock around the fi_deleg_file read in the SC_TYPE_DELEG path, matching the locking discipline of the find_any_file() arm, and replacing the BUG_ON with a graceful error return that cleans up the partially-initialized layout stateid. Fixes: c5c707f96fc9 ("nfsd: implement pNFS layout recalls") Cc: stable@vger.kernel.org Assisted-by: kres:claude-opus-4-7 Reported-by: Chris Mason Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260530-nfsd-fixes-v2-1-f27e8eb4d974@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/nfs4layouts.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c index bcf16dd07d488..d0b76aee54f83 100644 --- a/fs/nfsd/nfs4layouts.c +++ b/fs/nfsd/nfs4layouts.c @@ -167,9 +167,12 @@ nfsd4_free_layout_stateid(struct nfs4_stid *stid) list_del_init(&ls->ls_perfile); spin_unlock(&fp->fi_lock); - if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls) - vfs_setlease(ls->ls_file->nf_file, F_UNLCK, NULL, (void **)&ls); - nfsd_file_put(ls->ls_file); + if (ls->ls_file) { + if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls) + vfs_setlease(ls->ls_file->nf_file, F_UNLCK, NULL, + (void **)&ls); + nfsd_file_put(ls->ls_file); + } if (ls->ls_recalled) atomic_dec(&ls->ls_stid.sc_file->fi_lo_recalls); @@ -234,11 +237,17 @@ nfsd4_alloc_layout_stateid(struct nfsd4_compound_state *cstate, nfsd4_init_cb(&ls->ls_recall, clp, &nfsd4_cb_layout_ops, NFSPROC4_CLNT_CB_LAYOUT); - if (parent->sc_type == NFS4_DELEG_STID) + if (parent->sc_type == NFS4_DELEG_STID) { + spin_lock(&fp->fi_lock); ls->ls_file = nfsd_file_get(fp->fi_deleg_file); - else + spin_unlock(&fp->fi_lock); + } else { ls->ls_file = find_any_file(fp); - BUG_ON(!ls->ls_file); + } + if (!ls->ls_file) { + nfs4_put_stid(stp); + return NULL; + } if (nfsd4_layout_setlease(ls)) { nfs4_put_stid(stp); -- 2.53.0