• Geert Uytterhoeven's avatar
    ASoC: simple-card: Fix crash in asoc_simple_card_unref() · 7ddfdb5c
    Geert Uytterhoeven authored
    If asoc_simple_card_probe() fails, asoc_simple_card_unref() may be
    called before dev_set_drvdata(), causing a NULL pointer dereference in
    asoc_simple_card_unref():
    
        Unable to handle kernel NULL pointer dereference at virtual address 000000d4
        ...
        PC is at asoc_simple_card_unref+0x14/0x48
        LR is at asoc_simple_card_probe+0x3d4/0x40c
    
    This typically happens because asoc_simple_card_parse_of() returns
    -EPROBE_DEFER, but other failure modes are possible.
    devm_snd_soc_register_card()/snd_soc_register_card() may fail either
    before or after dev_set_drvdata().
    
    Pass a snd_soc_card pointer instead of a platform_device pointer to
    asoc_simple_card_unref() to fix this.
    
    Note that if CONFIG_OF_DYNAMIC=n, of_node_put() is a dummy, and gcc may
    optimize away the loop over card->dai_link, never actually dereferencing
    card, and thus avoiding the crash...
    Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
    Fixes: e512e001 ("ASoC: simple-card: Fix the reference count of device nodes")
    Signed-off-by: default avatarMark Brown <broonie@kernel.org>
    Cc: stable@vger.kernel.org
    7ddfdb5c
simple-card.c 15.7 KB