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 2C89D2D97B7; Thu, 17 Sep 2026 19:01:35 +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=1789671697; cv=none; b=nn9Rnf7mIwWIF/LCn8vzUWgfcHGN0MEJJW89eYl2TxY3gwPzz2IHn5y8pS15QOZRKI1AWU3/GM6rSYzk0ncIY4sPbhCj/yzqdxXjWtDWIh2aOvZge8qL4JRSdAi9GVVPoYtU7GJiX705WHPPSuprJHaRnNwCt+IXVRHtBHarGwQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789671697; c=relaxed/simple; bh=tus252Y7MlogNlMX9u/rAoZ+8BUaVsd+FzGDPoiDTk8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gRxRfB9KQeeGFDqnYOrowbqhwndPMOZ4itml7UBIOWtWwj3P7HcchlGgL3vLDkde4AbY89+QlndqLpZrE58Ou6ujTeX0BviO8tdKlBra0H7iDlmi2qtic0P9WgOyRZj9eaE1d3S6ubOC0qMu0eYZxUmzMa6+fJsjBKrPx4yHIi8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=d7TedrI/; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="d7TedrI/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1C481F000FF; Thu, 17 Sep 2026 19:01:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789671695; bh=5vaRfF3/oXSctHOp3Db1nPnIZI27pjZkJnkZV3fo86U=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=d7TedrI/5Qsk2IFGx6oJti02Bv0ZRsjwrtmgsBnI9LdKbx7bkPDWDRhbhPbGWRYED qXtT7mOe1xRTCS9Fk+LMAXIfcjNgv+hTqY2D59zhTuc/oKC3TCnzaxWpw9grmTuIM2 HQIYZe+HVR9oc0+4aD3sq3n96bXLloT+L5p382JU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jeff Layton , Chuck Lever , Sasha Levin Subject: [PATCH 6.12 1061/1102] NFSD: Prevent client use-after-free during close_lru reaping Date: Thu, 17 Sep 2026 16:16:44 +0100 Message-ID: <20260917151607.450612824@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151539.408551884@linuxfoundation.org> References: <20260917151539.408551884@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfs4state.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -6877,11 +6877,16 @@ 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);