From nobody Mon Feb 9 01:01:17 2026 Received: from mx0a-0064b401.pphosted.com (mx0a-0064b401.pphosted.com [205.220.166.238]) (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 E04F8187332; Fri, 25 Apr 2025 03:41:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.166.238 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745552466; cv=none; b=nO/gLtZYCXJLqnykLyphdLMAIMoRfsEX8blWdS+1RX5cbp8xiWIAqgvrCH7oz9Bk02sNlCU4fP4ytXNKywhpGlqZ5/WLVpWcd+ZYK2xeY5mxgfR35PC/AyNpS7lT+fDzY0TY1VhF9/ZjE6l65VEYZOC8pGE1bnKGxQPQpu9C/98= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745552466; c=relaxed/simple; bh=wPvyuyfU1DAjAWhrRG/W1tcYDV8l4b+Yl+1azMhL93k=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=sYrTk/pfwd/u3euZGm8oTiIOUmOkz6iP3Ibf0BOLuP8zCR1HyQYKvjKHbS2vufIHGEWmeOW5bVAHaGcRQ93TJQpfKpVV16qFIpybd+PVYGlzgwiyhaBk21Gnad4zNsVv4rAQ6z6JyfkbEAcgynxs7hurgTKxSgGQQ7nisU0Ba6M= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=windriver.com; spf=pass smtp.mailfrom=windriver.com; arc=none smtp.client-ip=205.220.166.238 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=windriver.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=windriver.com Received: from pps.filterd (m0250810.ppops.net [127.0.0.1]) by mx0a-0064b401.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 53P33LLm029783; Thu, 24 Apr 2025 20:41:00 -0700 Received: from ala-exchng02.corp.ad.wrs.com (ala-exchng02.wrs.com [147.11.82.254]) by mx0a-0064b401.pphosted.com (PPS) with ESMTPS id 466jhd384p-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Thu, 24 Apr 2025 20:41:00 -0700 (PDT) Received: from ALA-EXCHNG02.corp.ad.wrs.com (147.11.82.254) by ALA-EXCHNG02.corp.ad.wrs.com (147.11.82.254) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.43; Thu, 24 Apr 2025 20:40:59 -0700 Received: from pek-lpd-ccm6.wrs.com (147.11.136.210) by ALA-EXCHNG02.corp.ad.wrs.com (147.11.82.254) with Microsoft SMTP Server id 15.1.2507.43 via Frontend Transport; Thu, 24 Apr 2025 20:40:57 -0700 From: Lizhi Xu To: CC: , , , Subject: [PATCH] loop: Add sanity check for read/write_iter Date: Fri, 25 Apr 2025 11:40:57 +0800 Message-ID: <20250425034057.3133195-1-lizhi.xu@windriver.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <680a45db.050a0220.10d98e.000a.GAE@google.com> References: <680a45db.050a0220.10d98e.000a.GAE@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Authority-Analysis: v=2.4 cv=ZNDXmW7b c=1 sm=1 tr=0 ts=680b044c cx=c_pps a=K4BcnWQioVPsTJd46EJO2w==:117 a=K4BcnWQioVPsTJd46EJO2w==:17 a=XR8D0OoHHMoA:10 a=edf1wS77AAAA:8 a=hSkVLCK3AAAA:8 a=t7CeM3EgAAAA:8 a=5yON4tJlvpFzjYmBgeMA:9 a=DcSpbTIhAlouE1Uv7lRv:22 a=cQPPKAXgyycSBL8etih5:22 a=FdTzh2GWekK77mhwV6Dw:22 X-Proofpoint-ORIG-GUID: lqNWFcyHey-Bm6QNdnYGMW3-o9h4qBYy X-Proofpoint-GUID: lqNWFcyHey-Bm6QNdnYGMW3-o9h4qBYy X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNDI1MDAyNCBTYWx0ZWRfX7V26i8R6fC+b DFQHxqIDwy3XF8AlzTzA+TbNH+WWJ14inoiE2zBjce3R9em5gHWOCmnAIlBPhsDWnpMgtWaASeP cgJMZOx38Gku7zMr0jukIZW7BXoP/Q6Afw3eIAbO7q5avshA+/o0qwVtJc0WxiIjqWBnrRkWp34 4WTVOfxjTO3hlaxHLXoaSZBHiy3mubV/c15qEM4baziqeknKTRfXb3K423lmnR/CEVvHVpttXAh kecvMVstrmq7WvH2g/BcxvFgjU8X7H0utMGWHDGzSck+krI8+wd/BjTZeYzsCioYnNYCVUYSuNL IknxDUudOG2IozPKH8EC4Jez83rjK4Zyy5k9FWcgiYt1jLydwApUlcZt1/GSxZQxpPE5gmn7LlM JUYadnABwQd1w4An56dFfeWdfSny9qmAXxWYAjgbgh2hkAi6yAja+shDoGVhQZ/zn5Qun3an X-Sensitive_Customer_Information: Yes X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-04-25_01,2025-04-24_02,2025-02-21_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 priorityscore=1501 clxscore=1011 adultscore=0 spamscore=0 bulkscore=0 impostorscore=0 malwarescore=0 mlxlogscore=893 mlxscore=0 suspectscore=0 phishscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.21.0-2504070000 definitions=main-2504250024 Content-Type: text/plain; charset="utf-8" Some file systems do not support read_iter or write_iter, such as selinuxfs in this issue. So before calling them, first confirm that the interface is supported and then call it. Reported-by: syzbot+6af973a3b8dfd2faefdc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D6af973a3b8dfd2faefdc Signed-off-by: Lizhi Xu --- drivers/block/loop.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 674527d770dc..4f968e3071ed 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -449,10 +449,15 @@ static int lo_rw_aio(struct loop_device *lo, struct l= oop_cmd *cmd, cmd->iocb.ki_flags =3D IOCB_DIRECT; cmd->iocb.ki_ioprio =3D IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); =20 - if (rw =3D=3D ITER_SOURCE) - ret =3D file->f_op->write_iter(&cmd->iocb, &iter); - else - ret =3D file->f_op->read_iter(&cmd->iocb, &iter); + ret =3D 0; + if (rw =3D=3D ITER_SOURCE) { + if (likely(file->f_op->write_iter)) + ret =3D file->f_op->write_iter(&cmd->iocb, &iter); + } + else { + if (likely(file->f_op->read_iter)) + ret =3D file->f_op->read_iter(&cmd->iocb, &iter); + } =20 lo_rw_aio_do_completion(cmd); =20 --=20 2.43.0