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 863DF1F16B for ; Wed, 9 Sep 2026 00:25:16 +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=1788913517; cv=none; b=cPW6E00e7yiV2a+RmVwJvsULLuyXGc9OCnJif5Gls7UntiPQIVH4m8P6HX8tjq+saQt4ZsHTLDGDtD3dqAxEEMGEwaiU06Nbiq18zthuKHVNa6eiscG00LVpprvvw5V2KnlKxsbiPbig/JdjdU877vCqMFYMJO2xzGwq8rKv1XM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788913517; c=relaxed/simple; bh=9mAbltwDzlJ/HsbNLG7lQjY8uvsV6iXaOIHmSRNPXp4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=kvdXTWh13mrM+1oRfSAC+Wny8JSppTqP3eAHNwrsGRsxq6t34mYlNIcJUEIZRaUr1beuVrqxoJEZFXbU8t7LVri6Jg+Xd5ygrMvg1a9oay/LYck4w1Eq9Nhhtw6D8PQCw706eUJKl9rnL260sOxhn+wz+axudSrFGzqAWGUljf8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CBVcL5FT; 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="CBVcL5FT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC6A01F00AC4; Wed, 9 Sep 2026 00:25:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788913516; bh=StQHIZuTTRGjwmwlUHfeOq802Kd4s6RheoLI76a7ImE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=CBVcL5FTe+Mm0AEEfc+CpiHmqNCBw7TFAe+SDaQ+n4C6pJSgyb/fexnQNgdIkZHsQ ZmzP9jryV4kW8fJ5MOM2YEtCB0Xl7MfVx/a8BlLLdyvqfSj5+fnqpVNEZ6aYzruG/n 2dlVHqNs1BFVFiwxoTIUGpoOetgLIENmxrKrm3g25eJiHhFdvoLcSwj1pJiYAcqv3b 2qj0KKmgcmGMI+I8n6ZLVi+qS3lC4aRWSs3xSyxYyBAL1QYcPVJNmV4xJd/wzUBWYz mkpO6RfmcxS25xLh4k2e8sav3YxLymdoyygTAPU09ubdb6hQ5atKQjAW+ZttQLk5TI ComaA57cZzZew== From: Sasha Levin To: stable@vger.kernel.org Cc: Jeff Layton , Chuck Lever , Sasha Levin Subject: [PATCH 6.1.y 5/5] sunrpc: defer rq_argp and rq_resp free until after RCU grace period Date: Tue, 8 Sep 2026 20:25:11 -0400 Message-ID: <20260909002511.725380-5-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260909002511.725380-1-sashal@kernel.org> References: <2026090350-comment-projector-6988@gregkh> <20260909002511.725380-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jeff Layton [ Upstream commit c479bde671cbe2f9e152834a8b0eb7c3c295bbaf ] 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: Sasha Levin --- net/sunrpc/svc.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 3fe7152ee8bf5..c3d18ff3ce296 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -631,16 +631,23 @@ svc_release_buffer(struct svc_rqst *rqstp) } } +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) { 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 * -- 2.53.0