From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7005E2FF66C; Mon, 3 Nov 2025 11:01:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762167702; cv=none; b=LHGGgTu8kHHzF8C38GwdZ/5OPepEett5hKv/jWbrsvVdbf+v1Itf+maVfYidbFcncpSiuZbMmsf0mGfaEx6HZwQxqLYee8jNwTMcpwrGIXZuWWqAGalsQdc/o2PmCSXJvBddLHzkhKG2gdA8hd9wR3Pwal7DNngHPL8Odic6lqQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762167702; c=relaxed/simple; bh=7Yl7p/QKEuKHnvf3YHO1rOx7CdUWvLwG5swnB3bc+OE=; h=Message-ID:Date:MIME-Version:From:Subject:To:Cc:References: In-Reply-To:Content-Type; b=naK87HXK7MxLEyf+X7DAdO71pHYk8dnFQmC5THHtm3PQA47x39L6vYak4nmaR934RUPNPapT/pJmAGOW/Du+C5ykYiN6TpSRUXPA/TQ7LSOKRYgSqOcD2hVEnW1CqWRENRSGBk58ZnPXX3rhVuKJaQp+lIujK36yzRxTgCGi01c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OXLo1ILC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OXLo1ILC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B2D8FC4CEE7; Mon, 3 Nov 2025 11:01:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762167702; bh=7Yl7p/QKEuKHnvf3YHO1rOx7CdUWvLwG5swnB3bc+OE=; h=Date:From:Subject:To:Cc:References:In-Reply-To:From; b=OXLo1ILCSbQrT3q/OqOr+NGTkNoVDVspDRDFRbSItt1cMc4Z+ingzlppzx/jVjCfg cZ4dX+q471OUZpo/tnnFZL31Pu9ZPLn2o5Odly5z98UABy5SYz14FscVpBfO6c1T/P uhpUT572SQ1irzA/GgbcXLHVjd27sfUrGfu+OSGFl1MoeChH5c3jjNWd2i+oH4+Mf0 Ax1Fbh/bNNvc5o9gRBYEK0BZRDq/pi+1BSji9u/K7B0GR2zLVHhvPxYRM+mH3X9UY+ zJvuUHeX21OYk828hNWoxJLdHiMLBK3CkDNKABXlHdoNNAQlZ3xxtVY1Ajch3uUYO1 O4lV1mkHgioXQ== Message-ID: <9f9d2240-63be-4232-8ad6-44821d2b9177@kernel.org> Date: Mon, 3 Nov 2025 12:01:39 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Hans Verkuil Subject: Re: [PATCH V2] media: dvb-usb: Optimizing err() output To: Edward Adam Davis Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, mchehab@kernel.org, syzbot+480edd2cadb85ddb4bbe@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com References: <24d04c2c-50b1-48ec-8ba9-c09ef29fd3fd@kernel.org> Content-Language: en-US, nl In-Reply-To: <24d04c2c-50b1-48ec-8ba9-c09ef29fd3fd@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Also fix the Subject line to add "pctv452e:" as prefix. Regards, Hans On 03/11/2025 12:00, Hans Verkuil wrote: > On 14/10/2025 02:30, Edward Adam Davis wrote: >> 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=480edd2cadb85ddb4bbe >> Signed-off-by: Edward Adam Davis >> --- >> V1 -> V2: subject typos >> >> 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-usb/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, u8 addr, >> struct pctv452e_state *state = d->priv; >> u8 *buf; >> u8 id; >> - int ret; >> + int ret, plen = 0; > > Adding a plen variable isn't the right fix... > >> >> buf = kmalloc(64, GFP_KERNEL); >> if (!buf) >> @@ -432,6 +432,7 @@ static int pctv452e_i2c_msg(struct dvb_usb_device *d, u8 addr, >> if (snd_len > 64 - 7 || rcv_len > 64 - 7) >> goto failed; > > ...this check should be moved up to before the kmalloc and just return -EINVAL. > That also avoids incrementing state->c in that case. > > Regards, > > Hans > >> >> + plen = 7; >> buf[0] = SYNC_BYTE_OUT; >> buf[1] = id; >> buf[2] = PCTV_CMD_I2C; >> @@ -466,7 +467,7 @@ static int pctv452e_i2c_msg(struct dvb_usb_device *d, u8 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); >> >> kfree(buf); >> return ret; > >