From nobody Fri Dec 19 12:16:03 2025 Received: from out162-62-57-252.mail.qq.com (out162-62-57-252.mail.qq.com [162.62.57.252]) (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 407A226A087; Fri, 10 Oct 2025 15:27:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=162.62.57.252 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760110025; cv=none; b=TDcm2farymX+a0SQhGOeyr0hIQFj37PhqTnIok0rfWwQce4BW1Z7ipEpsRG0nTMtKyCgTeiu66BPpoQMJ+bidwQaDkfxmNwQg0iKxcUIngQ+X0Qt9EbH2mqt/BTUKSTRDqQtB1gkoFQuc9SS4xQSLx32ioZaUtHqadaVPULAtcs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760110025; c=relaxed/simple; bh=FoqhnH0aoPYtJFp9JGtXoN+k6yFcXvixrQP3VmDh8ys=; h=Message-ID:From:To:Cc:Subject:Date:In-Reply-To:References: MIME-Version; b=pPcOBi0yoJJpBVedYQ4SfUT5JLQbijOPEL1Z81JyT2NiI9/kBy7eQISONFLtoOtIraCpzN8k7Y9Wym3B2kbBsRnKE0D+xiaefwkSJJx0de1MYQEexnwyaK5QOibqn9rp1EkLn4+peER0T2G0EsYcNc1y9OhzSW4EQkvdPZyAZbY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com; spf=pass smtp.mailfrom=qq.com; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b=kQf++FDe; arc=none smtp.client-ip=162.62.57.252 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=qq.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=qq.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=qq.com header.i=@qq.com header.b="kQf++FDe" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qq.com; s=s201512; t=1760109710; bh=Or25gIiKy8boPBkk79EZPJZ6wSZGAllmnA2wLhBp+uQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=kQf++FDej6cmeAzlzrizBzCQRx8fBbQ79Sg4AKWl/fDPA1DII2n/zAtxpPPyP6ZIO HpyFhn09GH2RJ1XFk7977G+wodpgWk5nTjb6HqT7XaTBHw61BCcKOFkI3Qaj0TaHV8 cxBNKbLU9vhrs5thmPep5NFdRUbsAC7qPobDeRuw= Received: from pek-lxu-l1.corp.ad.wrs.com ([111.198.230.220]) by newxmesmtplogicsvrszb20-0.qq.com (NewEsmtp) with SMTP id 56FA1A4E; Fri, 10 Oct 2025 23:21:47 +0800 X-QQ-mid: xmsmtpt1760109707tibdhsrd0 Message-ID: X-QQ-XMAILINFO: NVJ0hJNx7N5SiqtozZbheU49yv/RiquKVrW2qkWLlsO5mGucU4DBndxbIYERFB AJFz7rnm5pENdTHXM3Ht5VqTX0xEpfhLlA2xPzNX+/PiRR/zAGJFAosJlM762NSrFEf5R67So77g 1xrLVahRJWPBNZyFxZORLquNJP2DPw10rb41eiGGOMYr9gWeeqpqOJs7t5pCDNWx2eDCe2Ms2622 9zn/Muluqr9jAlIkh/P8A4qlh3KQYeHnS1U6aQbKnCTk6oUTp8FahBkscUnMniRemc+IKnSrlILq MZLgqpqP8odA0h5vbmf/bcfItOqjfBeqtatdNVAT8ibOiKkv3JjrHRkHSuYojg5N/+MmmCvA3hoc 3lp4dmH3pqJ06HMnQARug9yrPZJeYJ4IsX05QpLsx/QTXVH0g0F3GMORDoD5EP43SS/XT+a3kL3Q bDPENylRj+TtKGmG+lg13Bs60m61wRacEDhdQ9A7xNdVHoQPyxDbpyCSVDWKzPylyjg9MghJBAG3 JkW9cl+E/tQec3x+rxxu/I/AuFzdRqPCR+Qr+kS+rhFQ0rDlCjCletGR/sAnBzmxW7vCm9G24z3g JrkGdZ+/4zTyVdxXbTQKUXVQQwycHPx3iXM4Wcvvl8FKlIJc1PxwTHRZcbpbN6F190f8HoSvG7DN FlYGiz9QcI5KS3aOvL/WZGI/t2y54M8ZTvMB2hMVa/BNh+TYwhuAtennf2vPYFpBMIhvtD9nCSZA dtIjmcqv8PlzLF+MDFi2VaUdgzokwf/cST5IqdRtg62VJ30pRwfbT0wZwZa5fq3jgRwuR+16H82a 4tfO4s8hba/D/ZqNxcrUP/n3M8nXs0OuNRzwRoGA0zrNbd8ise7QuveqQCzZr4XDJn5LR5y2QXek bjLej5S7Z20sh0xzacS+QPhSwwO0JhN0S5KZs4iF80HWd0AamEFxylQmLM5SHPtaMkZ0WMJtKtlt CEnVQ9L2E10Sdd+5jxgFwDn6CExXsIwrUv9UrFb7seTm2xi2lfw62qsdg/HMBI X-QQ-XMRINFO: NI4Ajvh11aEj8Xl/2s1/T8w= From: Edward Adam Davis To: syzbot+480edd2cadb85ddb4bbe@syzkaller.appspotmail.com Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, mchehab@kernel.org, syzkaller-bugs@googlegroups.com Subject: [PATCH] meida: dvb-usb: Optimizing err() output Date: Fri, 10 Oct 2025 23:21:48 +0800 X-OQ-MSGID: <20251010152147.2167496-2-eadavis@qq.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <68e8894e.050a0220.91a22.0056.GAE@google.com> References: <68e8894e.050a0220.91a22.0056.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 Content-Type: text/plain; charset="utf-8" syzbot reported a uninit-value in pctv452e_i2c_msg. [1] When the snd_len or rcv_len check fails and jumps to failed, buf is uninitialized, triggering the uninit-value issue. Setting the err() output buf byte count to 0 before jumping to failed before initializing buf and setting it to 7 after initializing buf avoids this warning. [1] BUG: KMSAN: uninit-value in hex_string+0x681/0x740 lib/vsprintf.c:1220 pctv452e_i2c_msg+0x82a/0x8f0 drivers/media/usb/dvb-usb/pctv452e.c:467 pctv452e_i2c_xfer+0x2e6/0x4c0 drivers/media/usb/dvb-usb/pctv452e.c:502 Reported-by: syzbot+480edd2cadb85ddb4bbe@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D480edd2cadb85ddb4bbe Signed-off-by: Edward Adam Davis --- drivers/media/usb/dvb-usb/pctv452e.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/media/usb/dvb-usb/pctv452e.c b/drivers/media/usb/dvb-u= sb/pctv452e.c index 5094de9a312e..3b6e86a8e9ff 100644 --- a/drivers/media/usb/dvb-usb/pctv452e.c +++ b/drivers/media/usb/dvb-usb/pctv452e.c @@ -420,7 +420,7 @@ static int pctv452e_i2c_msg(struct dvb_usb_device *d, u= 8 addr, struct pctv452e_state *state =3D d->priv; u8 *buf; u8 id; - int ret; + int ret, plen =3D 0; =20 buf =3D kmalloc(64, GFP_KERNEL); if (!buf) @@ -432,6 +432,7 @@ static int pctv452e_i2c_msg(struct dvb_usb_device *d, u= 8 addr, if (snd_len > 64 - 7 || rcv_len > 64 - 7) goto failed; =20 + plen =3D 7; buf[0] =3D SYNC_BYTE_OUT; buf[1] =3D id; buf[2] =3D PCTV_CMD_I2C; @@ -466,7 +467,7 @@ static int pctv452e_i2c_msg(struct dvb_usb_device *d, u= 8 addr, failed: err("I2C error %d; %02X %02X %02X %02X %02X -> %*ph", ret, SYNC_BYTE_OUT, id, addr << 1, snd_len, rcv_len, - 7, buf); + plen, buf); =20 kfree(buf); return ret; --=20 2.43.0