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 56FF437C106; Fri, 4 Sep 2026 05:51:19 +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=1788501080; cv=none; b=XYtIrAwRrD7elB/r/Q76wCZm2555mDoEabl2JKUdwN2uGFi9JcE83nDiyPMdDrQdrefwflwDNBiYsvSADv5tXkSJYXuOcxkGmNdMuTUffDnXEu1wKIIjh6QvptqlQrxSfHvOC1LGFGgqYJ98yY7R6wTLro0gYrbYuXVuce1HHeE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788501080; c=relaxed/simple; bh=0m4ITbiJ52g1jOA7rUXbWkQtQ7wgDSflbwWY4q3bbzM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=XU/wR4J61qO6WJPptymbIf6WGRMMBoLyQh2uWkTI/mGNX4jTNeWoDNs7XP3g1PIgn7snMv8wlPXZZy1zNx08E7L96BanLJDR8eeTsfiLkpCikbDTCyKEjhKB8JafLGcbCCwJWW2++NCtwqf12TKipFIjEbkNqiMs0Z6+EwJO+V4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=iAC7Kq0P; 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="iAC7Kq0P" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B212B1F00A3D; Fri, 4 Sep 2026 05:51:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788501079; bh=dL6oBLolo61PVV9QMLYe5GhDqGJuvVMKfJQpybe95Ys=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=iAC7Kq0PhcjzJ5MR2lLvuBf85E6aPaeMGDbtOQ+DcCUHIyEkQja+kdZWycJIi/6dS GScbNpr/dTxIi6Vo/S/tEZIeBMVsPx8zCZOtfpsNvA8+c9KStmEMsFBe+Pq37LCh/M u1LEoJ0xORhDL52FMVVc/b6sH90eOXh9tLgmQ53o= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jeff Layton , Chuck Lever Subject: [PATCH 6.18 283/552] sunrpc: defer rq_argp and rq_resp free until after RCU grace period Date: Fri, 4 Sep 2026 06:57:20 +0200 Message-ID: <20260904045756.377784635@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045747.813364717@linuxfoundation.org> References: <20260904045747.813364717@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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeff Layton commit c479bde671cbe2f9e152834a8b0eb7c3c295bbaf upstream. svc_rqst_free() frees rqstp->rq_argp and rqstp->rq_resp synchronously via kfree(), but defers the rqstp struct free via kfree_rcu(). After svc_exit_thread() calls list_del_rcu() and svc_rqst_free(), there is a window where RCU readers that started before list_del_rcu() can still traverse the thread list and find the rqstp. These readers (e.g. nfsd_nl_rpc_status_get_dumpit()) dereference rqstp->rq_argp, which has already been freed — a use-after-free. Fix this by moving the kfree of rq_argp and rq_resp into an explicit call_rcu() callback alongside the struct free. Resources not accessed by RCU readers (bvec, buffer pages, scratch folio, auth_data) remain synchronously freed. Fixes: 812443865c5f ("sunrpc: add a rcu_head to svc_rqst and use kfree_rcu to free it") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260611-nfsd-testing-v2-4-5b90e276f2d9@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/svc.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -723,6 +723,15 @@ svc_release_buffer(struct svc_rqst *rqst kfree(rqstp->rq_pages); } +static void svc_rqst_free_rcu(struct rcu_head *head) +{ + struct svc_rqst *rqstp = container_of(head, struct svc_rqst, rq_rcu_head); + + kfree(rqstp->rq_resp); + kfree(rqstp->rq_argp); + kfree(rqstp); +} + static void svc_rqst_free(struct svc_rqst *rqstp) { @@ -731,10 +740,8 @@ svc_rqst_free(struct svc_rqst *rqstp) svc_release_buffer(rqstp); if (rqstp->rq_scratch_folio) folio_put(rqstp->rq_scratch_folio); - kfree(rqstp->rq_resp); - kfree(rqstp->rq_argp); kfree(rqstp->rq_auth_data); - kfree_rcu(rqstp, rq_rcu_head); + call_rcu(&rqstp->rq_rcu_head, svc_rqst_free_rcu); } static struct svc_rqst *