• Gustavo A. R. Silva's avatar
    ALSA: emux: Fix potential Spectre v1 vulnerabilities · a53ba068
    Gustavo A. R. Silva authored
    commit 4aea96f4237cea0c51a8bc87c0db31f0f932f1f0 upstream.
    
    info.mode and info.port are indirectly controlled by user-space,
    hence leading to a potential exploitation of the Spectre variant 1
    vulnerability.
    
    These issues were detected with the help of Smatch:
    
    sound/synth/emux/emux_hwdep.c:72 snd_emux_hwdep_misc_mode() warn: potential spectre issue 'emu->portptrs[i]->ctrls' [w] (local cap)
    sound/synth/emux/emux_hwdep.c:75 snd_emux_hwdep_misc_mode() warn: potential spectre issue 'emu->portptrs' [w] (local cap)
    sound/synth/emux/emux_hwdep.c:75 snd_emux_hwdep_misc_mode() warn: potential spectre issue 'emu->portptrs[info.port]->ctrls' [w] (local cap)
    
    Fix this by sanitizing both info.mode and info.port before using them
    to index emu->portptrs[i]->ctrls, emu->portptrs[info.port]->ctrls and
    emu->portptrs.
    
    Notice that given that speculation windows are large, the policy is
    to kill the speculation on the first load and not worry if it can be
    completed with a dependent load/store [1].
    
    [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2Signed-off-by: 's avatarGustavo A. R. Silva <gustavo@embeddedor.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: 's avatarTakashi Iwai <tiwai@suse.de>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    a53ba068
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