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 B1ABF299959 for ; Mon, 7 Sep 2026 23:02:57 +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=1788822178; cv=none; b=QUWVYJYyvFm0MrBynKdg9GwnaZAuNkPJu7fi5w6bxTLE0Gi4HieQUtN28LpllMVoDi/ji4Ans/YhKxRKEn9YJXjwswoXiutjuKH/4i6Cz58Gv9LhdJxOK+39cmjWf97aZjxnQxw/3wa/KSw4MDO/7yvGvGZceJxq/6wrZOMAueM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788822178; c=relaxed/simple; bh=TbgiT1FT2F5daIqObjgX0hP5SpXZ9g+i80Kv14TVxhE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ji3csFL8xQAoLF/duBI1lxe2GNDRvVYOewQJ39IC+Lzcf9BJ144l5NcP+rxzplyWvi+cGU0+4pBIEvHHFL3ItUjyLba0Gb0mQf0MD6josh+ovPJSxh3DDPw0HA4rVOycuS2GggjOEjHpvMFW+woacS5GkwLSbJ1UUj+On4+wUKk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oO3vCM7/; 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="oO3vCM7/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20EB01F00A3A; Mon, 7 Sep 2026 23:02:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788822177; bh=tAg8XWJICyAJoJuwDFJyXg8gyP1wpeyt40FR0ClSpVA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=oO3vCM7/uQy3N6sj2MEEpiw5j2n0v7ebPEws0yPkNrgqT6c4qY4j7dfbL2dzxgLcU AEFGnhhIANiDjAuPO2k+NhFiGvmVkeb0e+DRswWHJ4m0kkqwdrUl4nnGc09huWWbMo 3dVOFTofT3qpY6WLS9o+R2IT06p3mi04jqNqoD87URzt/8zIUirLAgwv9Ypj7xZCaG qXgMuQBKjX97AQPscnDLqcyzLH6NnfUkIEpnHBjuyPUQa2CP/5dwjLo6+4V+E3XWnJ 8tRf74Vve/+53sa8EC1WiVxi2kk+IEFwjvuHjjxFOUd9s5iAHMaARbrWqkURFg/5s4 TDyxiwDfPoe7g== From: Sasha Levin To: stable@vger.kernel.org Cc: Chuck Lever , Jeff Layton , Sasha Levin Subject: [PATCH 6.12.y 4/4] NFSD: Prevent client use-after-free during close_lru reaping Date: Mon, 7 Sep 2026 19:02:53 -0400 Message-ID: <20260907230253.720658-4-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260907230253.720658-1-sashal@kernel.org> References: <2026090305-unmasking-excuse-7fa0@gregkh> <20260907230253.720658-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chuck Lever [ Upstream commit 2330b788d732f43668b965b3105b37ceb276dfea ] An nfs4_openowner left on nn->close_lru after its final CLOSE keeps its last closed stateid in oo_last_closed_stid, holding only a raw pointer to its nfs4_client. The laundromat reaps timed-out entries, drops nn->client_lock, and calls nfs4_put_stid(), which dereferences the client through cl_lock. Nothing pins the client across that window, so a concurrent force_expire_client() can free it and nfs4_put_stid() reads freed memory. __destroy_client() hits the same race, walking clp->cl_openowners without cl_lock. Pin the client with cl_rpc_users before dropping client_lock, and skip clients already expiring. __destroy_client() then cleans up its own close_lru entries through release_last_closed_stateid(), so teardown no longer races the laundromat. Fixes: 217526e7ecc9 ("nfsd: protect the close_lru list and oo_last_closed_stid with client_lock") Cc: stable@vger.kernel.org Reviewed-by: Jeff Layton Link: https://patch.msgid.link/20260709-cel-v4-8-1d519d9be0cb@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/nfs4state.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index a20f4b72033ff..be4c01700bf15 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -6847,11 +6847,16 @@ nfs4_laundromat(struct nfsd_net *nn) if (!state_expired(<, oo->oo_time)) break; list_del_init(&oo->oo_close_lru); + clp = oo->oo_owner.so_client; + if (is_client_expired(clp)) + continue; stp = oo->oo_last_closed_stid; oo->oo_last_closed_stid = NULL; + atomic_inc(&clp->cl_rpc_users); spin_unlock(&nn->client_lock); nfs4_put_stid(&stp->st_stid); spin_lock(&nn->client_lock); + put_client_no_renew_locked(clp); } spin_unlock(&nn->client_lock); -- 2.53.0