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Date:   Mon, 26 Apr 2021 18:01:26 +0200
Message-ID: <s5hzgxl11d5.wl-tiwai@suse.de>
From:   Takashi Iwai <tiwai@suse.de>
To:     Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Cc:     perex@perex.cz, tiwai@suse.com, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sound/isa/ib: Fix two use after free in snd_sb_qsound_build
In-Reply-To: <20210426145541.8070-1-lyl2019@mail.ustc.edu.cn>
References: <20210426145541.8070-1-lyl2019@mail.ustc.edu.cn>
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On Mon, 26 Apr 2021 16:55:41 +0200,
Lv Yunlong wrote:
> 
> In snd_sb_qsound_build, snd_ctl_add(..,p->qsound_switch...) and
> snd_ctl_add(..,p->qsound_space..) are called. But the second
> arguments of snd_ctl_add() could be freed via snd_ctl_add_replace()
> ->snd_ctl_free_one(). After the error code is returned,
> snd_sb_qsound_destroy(p) is called in __error branch.
> 
> But in snd_sb_qsound_destroy(), the freed p->qsound_switch and
> p->qsound_space are still used by snd_ctl_remove().
> 
> My patch set p->qsound_switch and p->qsound_space to NULL if
> snd_ctl_add() failed to avoid the uaf bugs. But these codes need
> to further be improved with the code style.
> 
> Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>

Thanks, applied now.


Takashi