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 946AC258CCB for ; Wed, 10 Sep 2025 06:41:34 +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=1757486494; cv=none; b=lB+ql6PYB/Q3AjKB+69fOM3x0fYfFSlAWT6ZuiuKWcBR13N/HC1O7kYpp496oRKyo1wxjNj1V2WUzHGpLUFk0QxNrSDQR0i/tzqnBslAW7mx75frVQ8fKmaQc4i4SSNWW3oJJLXnpUHBU8pkP4+2Rmt8bmumS5jVIsmTF233yYo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757486494; c=relaxed/simple; bh=Fd2xvBWLktZ5YdvgnEXWK1lN/vFyVcJ4P5YZTVrvPe0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mBBTQimtuEjVBm3evVjvmG76biqO8yk/H6HSvUlo9Aq/lO5L/f36MKMspNGc89hX8BqtvY/Y34ig+vlANnTLaY0POWdLM6k0/6aCMYAiNJpfjVxp6r3J5MXlWEarc+umMmtyJvEqYFtE+fZi9Uy9wddblTbW7uWUPyGgFS8khOc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=glP6W9NG; 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="glP6W9NG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 459C7C4CEF0; Wed, 10 Sep 2025 06:41:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757486494; bh=Fd2xvBWLktZ5YdvgnEXWK1lN/vFyVcJ4P5YZTVrvPe0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=glP6W9NGui1n2FonGuxXhhMV+aSUbbkuWxYaMwGVz8xeq1BgDRraGImossOs8grUi 5XexvTe8L3fv0oMkOsPZpGxpbDkCn6ch9EGMdiq31b528zJiM3H5/MPxlidCQjp7S2 ds0DMJ3SDKP5nCu+SkWIQcdJSDFcswoUNUpnZBEGHdqOpS1DseLmS29Lvz5hCJMPM3 HbV5Lkq5zkVC0tRXvZZK+h+Iq2XzQSPROpyLBIPVMjyJc3+DlUZnkWxNXnAnsXwARn BfbZEyVARbVKYJMrSHBrQQCkIkGP8exzzjFigHaB185cOk042CZT4fv0e617HXMeKp 5Q9Rlxo09OknQ== Message-ID: <51222649-6f41-4030-baaa-7b98b241de98@kernel.org> Date: Wed, 10 Sep 2025 08:41:31 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: vt: add support for smput/rmput escape codes To: "Colin King (gmail)" , Calixte Pernot , Greg Kroah-Hartman Cc: "linux-kernel@vger.kernel.org" References: <5002d4f9-4999-4a84-9329-edb20098fd7a@gmail.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 09. 09. 25, 21:15, Colin King (gmail) wrote: > Hi, > > Static analysis on linux-next detected an issue with the following commit: > > commit 23743ba64709a9c137c1b928f8b8e00d846af9cc > Author: Calixte Pernot > Date:   Mon Aug 25 14:56:09 2025 +0200 > >     vt: add support for smput/rmput escape codes > > > The issue is as follows in drivers/tty/vt/vt.c function vc_deallocate, > with my nodes prefixed by ##### > > struct vc_data *vc_deallocate(unsigned int currcons) > { ... >     ##### vc is potentially null and being dereferenced below: > >         if (vc->vc_saved_screen != NULL) { >                 kfree(vc->vc_saved_screen); >                 vc->vc_saved_screen = NULL; >         } >         return vc; > } > > > The issue is that vc is only set in the if (vc_cons_allocated(currcons)) > if block, and when it is not set, we end up with a null pointer de- > reference on the if (vc->vc_saved_screen != NULL) check. > > I suggest moving that latter check into the earlier if block. Agreed: https://lore.kernel.org/all/tencent_CAD45DB31906CF890DBB25AB0DED12205D07@qq.com/ thanks, -- js suse labs