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    Subject[PATCH 3.2 048/106] ASoC: Fix use-after-free at card unregistration
    3.2.93-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Takashi Iwai <tiwai@suse.de>

    commit 4efda5f2130da033aeedc5b3205569893b910de2 upstream.

    soc_cleanup_card_resources() call snd_card_free() at the last of its
    procedure. This turned out to lead to a use-after-free.
    PCM runtimes have been already removed via soc_remove_pcm_runtimes(),
    while it's dereferenced later in soc_pcm_free() called via
    snd_card_free().

    The fix is simple: just move the snd_card_free() call to the beginning
    of the whole procedure. This also gives another benefit: it
    guarantees that all operations have been shut down before actually
    releasing the resources, which was racy until now.

    Reported-and-tested-by: Robert Jarzmik <robert.jarzmik@free.fr>
    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Mark Brown <broonie@kernel.org>
    [bwh: Backported to 3.2: adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    sound/soc/soc-core.c | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    --- a/sound/soc/soc-core.c
    +++ b/sound/soc/soc-core.c
    @@ -1574,6 +1574,9 @@ static int soc_cleanup_card_resources(st
    flush_delayed_work_sync(&rtd->delayed_work);
    }

    + /* free the ALSA card at first; this syncs with pending operations */
    + snd_card_free(card->snd_card);
    +
    /* remove auxiliary devices */
    for (i = 0; i < card->num_aux_devs; i++)
    soc_remove_aux_dev(card, i);
    @@ -1590,9 +1593,7 @@ static int soc_cleanup_card_resources(st
    snd_soc_dapm_free(&card->dapm);

    kfree(card->rtd);
    - snd_card_free(card->snd_card);
    return 0;
    -
    }

    /* removes a socdev */
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