ALSA: sb: Fix two use after free in snd_sb_qsound_build
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> Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20210426145541.8070-1-lyl2019@mail.ustc.edu.cn Signed-off-by: Takashi Iwai <tiwai@suse.de>
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@ -1045,10 +1045,14 @@ static int snd_sb_qsound_build(struct snd_sb_csp * p)
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spin_lock_init(&p->q_lock);
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if ((err = snd_ctl_add(card, p->qsound_switch = snd_ctl_new1(&snd_sb_qsound_switch, p))) < 0)
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if ((err = snd_ctl_add(card, p->qsound_switch = snd_ctl_new1(&snd_sb_qsound_switch, p))) < 0) {
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p->qsound_switch = NULL;
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goto __error;
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if ((err = snd_ctl_add(card, p->qsound_space = snd_ctl_new1(&snd_sb_qsound_space, p))) < 0)
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}
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if ((err = snd_ctl_add(card, p->qsound_space = snd_ctl_new1(&snd_sb_qsound_space, p))) < 0) {
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p->qsound_space = NULL;
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goto __error;
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}
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return 0;
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