From nobody Mon Feb 9 06:36:13 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1E1AFC77B61 for ; Thu, 13 Apr 2023 09:21:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230153AbjDMJVR (ORCPT ); Thu, 13 Apr 2023 05:21:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229526AbjDMJVP (ORCPT ); Thu, 13 Apr 2023 05:21:15 -0400 Received: from a11-129.smtp-out.amazonses.com (a11-129.smtp-out.amazonses.com [54.240.11.129]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90F7D19AF; Thu, 13 Apr 2023 02:21:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=gwkuid74newif2lbp44dedrl2t4vmmbs; d=benbenng.net; t=1681377673; h=Subject:From:To:Cc:Date:Mime-Version:Content-Type:Content-Transfer-Encoding:References:Message-Id; bh=iCGZGKi5slX3+1EbZTs0K5lMxThH+s23lVBYdgse0I4=; b=dlXM0RiS+bkfvggjXjPyBfra2Ys+k+cPbgT4qIBDtC9qV7H8zF0wgVzGG0/nJfRA LxR8YxEr2hW86KQYAzg+NDcj2ZJi/dSwj5OEjtIcHVr9imYmF/QZVAEpBB7BHhF1Jrc yRzzUaNovUpPZ4qeQfpcgSfNq0v6g3iWyckCfifIBu7vwuEVFAS3KoxK+aJkTqacubu 2Y3xtkdqp6Z6MLlcIsuZx4Iij9oPVmxmSlbiypjCn8HP3vUxdamXbnZwXMnDnLxgxpd tKhGWmm2rbjM1kdaMYFNILIV1D7q0hLTsDbu5W/4e5lS+o0vdTHExkzku7K8yPJrHr7 8pEdPHNA4A== DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=224i4yxa5dv7c2xz3womw6peuasteono; d=amazonses.com; t=1681377673; h=Subject:From:To:Cc:Date:Mime-Version:Content-Type:Content-Transfer-Encoding:References:Message-Id:Feedback-ID; bh=iCGZGKi5slX3+1EbZTs0K5lMxThH+s23lVBYdgse0I4=; b=O5xpWDesy/hJag71jGjX6AgswpCtnGJulyPR0BS0RRk+bCsgMW/CnnteBDlOoNHh 0kAjpSf6xKrUhzfCsQYCuy4FYY2Z3YGJ2iLQ1+dJ2hyfCHtMxwikL6SmQFV8TMdKzKy jm5wIM89DS99ICEu30a1OGlfYn20ugayypjSMF88= Subject: [PATCH] Initialization of read buffer for dib3000_read_reg From: =?UTF-8?Q?Kernel-Development?= To: =?UTF-8?Q?mchehab=40kernel=2Eorg?= Cc: =?UTF-8?Q?linux-media=40vger=2Ekernel=2Eorg?= , =?UTF-8?Q?linux-kernel=40vger=2Ekernel=2E?= =?UTF-8?Q?org?= , =?UTF-8?Q?skhan=40linuxfo?= =?UTF-8?Q?undation=2Eorg?= , =?UTF-8?Q?linux-kernel-mentees=40lists=2Elinuxfoundation=2Eorg?= , =?UTF-8?Q?syzbot+c88fc0ebe0d5935c70da=40syzkaller=2Eappspotmail=2Ecom?= , =?UTF-8?Q?Kernel-Development?= Date: Thu, 13 Apr 2023 09:21:13 +0000 Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable References: <20230413091841.22000-1-kdev@benbenng.net> X-Mailer: Amazon WorkMail Thread-Index: AQHZbelJ3+E1CTjNR3uk6Rz3nyFiTw== Thread-Topic: [PATCH] Initialization of read buffer for dib3000_read_reg X-Original-Mailer: git-send-email 2.39.2 X-Wm-Sent-Timestamp: 1681377672 Message-ID: <0100018779eb40dc-cee9e39d-5d87-4733-83db-eca5218fcc8f-000000@email.amazonses.com> Feedback-ID: 1.us-east-1.LF00NED762KFuBsfzrtoqw+Brn/qlF9OYdxWukAhsl8=:AmazonSES X-SES-Outgoing: 2023.04.13-54.240.11.129 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This is a patch that fixes a bug: KMSAN: uninit-value in dib3000mb_attach (2) Local variable u8 rb[2] is not initialized as it is used as read buffer for i2c_transfer(). It is expected that i2c_transfer() should fill in the buffer before the target function returns rb's content. However error handling of i2c_transfer is not done, and on occasions where the read fails, uninitialized rb value will be returned. The usage of this function, defined as macro rd() in drivers/media/dvb-frontends/dib3000mb_priv,h, does not expect any error to occur. Adding error handling here might involve significant code changes. Thus 0-initialization is done on rb. This might affect some logic on error case as the use of the return value is used as boolean and flags. Reported-by: syzbot+c88fc0ebe0d5935c70da@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=3D2f4d19de8c9e9f0b9794e53ca54d68= e0ffe9f068 Signed-off-by: (Ben) HokChun Ng --- drivers/media/dvb-frontends/dib3000mb.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/media/dvb-frontends/dib3000mb.c b/drivers/media/dvb-fr= ontends/dib3000mb.c index a6c2fc4586eb..0dd96656aaf4 100644 --- a/drivers/media/dvb-frontends/dib3000mb.c +++ b/drivers/media/dvb-frontends/dib3000mb.c @@ -50,15 +50,19 @@ MODULE_PARM_DESC(debug, "set debugging level (1=3Dinfo,= 2=3Dxfer,4=3Dsetfe,8=3Dgetfe (|-a =20 static int dib3000_read_reg(struct dib3000_state *state, u16 reg) { + int errno; u8 wb[] =3D { ((reg >> 8) | 0x80) & 0xff, reg & 0xff }; - u8 rb[2]; + u8 rb[2] =3D { 0, 0 }; struct i2c_msg msg[] =3D { { .addr =3D state->config.demod_address, .flags =3D 0, .buf =3D w= b, .len =3D 2 }, { .addr =3D state->config.demod_address, .flags =3D I2C_M_RD, .buf =3D r= b, .len =3D 2 }, }; =20 - if (i2c_transfer(state->i2c, msg, 2) !=3D 2) - deb_i2c("i2c read error\n"); + errno =3D i2c_transfer(state->i2c, msg, 2); + if (errno !=3D 2) { + deb_i2c("i2c read error (errno: %d)\n", -errno); + return 0; + } =20 deb_i2c("reading i2c bus (reg: %5d 0x%04x, val: %5d 0x%04x)\n",reg,reg, (rb[0] << 8) | rb[1],(rb[0] << 8) | rb[1]); --=20 2.39.2