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 76D694B488E for ; Tue, 8 Sep 2026 22:36:58 +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=1788907022; cv=none; b=YyXnARF2Nf6VnJ32eRXBP76iSG9J/j09/Ts1+cKL5RNv7oc9ZW825toCkWN7XWO+6Q0U1B9/cd4RSXYxm9lO0k9dcBHE0lIJ3PtcrUc5gfoEgNLY/VF+ujSLbvFEI1p1Nvuvnhky0PBvLTx1VUMZDXquH1kaBMbY24N4lSxJrt0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788907022; c=relaxed/simple; bh=jaoaGgnFupWl/bOqsIj1HjGwvW0euWWc3X3zFYsylbQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=MFkoiXV+G8GPUIRT1bULQ84eK3Em7iWnIk/vyoL4+8iolc+Kyk2kf+1h5UK7wYT5PmePG+fiGdFP94yZ/WFYMSiXuaiXdswhkTC83M3ekrp53HCDQux8upEQuyf1DN8bsvuSoKBUSKuN6H/A5rYtv4hSmphmMnJZgcKtVT85ErM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ouiCb9Bd; 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="ouiCb9Bd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A54FE1F00A3E; Tue, 8 Sep 2026 22:36:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788907017; bh=9edE442dsGadAl7oWAflMMCvz8YLqP2Eqj0wlH263mU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ouiCb9BdIE/xl/nPTfRbrBFF/vfm/G/Etm80qfHhLImlC587gERpJYYC4NsRA3zcl VABlX6UUhjTx8+3DQlepV6oJhU6jpORAIxL8QS3327g4/7lg87GfguZctJb/Qe4H/t DR5hXVNwTDTrh2GBR4aqLV1w1Zr7r+j+feT8XwuF0yz32SnPu0l7yG15vmGpaxbN0X L3rAx2Vat6DmsJtsJb/11irwjMIYxIhYktECZJIZPTJRocKAhLg+imf30RI2L9X+tx 9ODtxhSGjoo57VreETQx2ysn/np6h+ykgGJjOlr2RXH30SjaImlKqHnIqux7Wjcbix mdAc9a4kg3Rgw== From: Sasha Levin To: stable@vger.kernel.org Cc: Jeff Layton , Chuck Lever , Sasha Levin Subject: [PATCH 6.6.y 7/7] sunrpc: defer rq_argp and rq_resp free until after RCU grace period Date: Tue, 8 Sep 2026 18:36:50 -0400 Message-ID: <20260908223651.501880-7-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260908223651.501880-1-sashal@kernel.org> References: <2026090350-breeze-repugnant-70de@gregkh> <20260908223651.501880-1-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 bfd685dfc70e9..b6c4287077fbd 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -677,6 +677,15 @@ svc_release_buffer(struct svc_rqst *rqstp) put_page(rqstp->rq_pages[i]); } +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) { @@ -684,10 +693,8 @@ 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 * -- 2.53.0