From: Takashi Iwai tiwai@suse.de
commit f9f0e9ed350e15d51ad07364b4cf910de50c472a upstream.
The bmControls (for UAC1) or bmMixerControls (for UAC2/3) bitmap has a variable size depending on both input and output pins. Its size is to fit with input * output bits. The problem is that the input size can't be determined simply from the unit descriptor itself but it needs to parse the whole connected sources. Although the uac_mixer_unit_get_channels() tries to check some possible overflow of this bitmap, it's incomplete due to the lack of the evaluation of input pins.
For covering possible overflows, this patch adds the bitmap overflow check in the loop of input pins in parse_audio_mixer_unit().
Fixes: 0bfe5e434e66 ("ALSA: usb-audio: Check mixer unit descriptors more strictly") Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- sound/usb/mixer.c | 36 ++++++++++++++++++++++++++++-------- 1 file changed, 28 insertions(+), 8 deletions(-)
--- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -739,7 +739,6 @@ static int uac_mixer_unit_get_channels(s struct uac_mixer_unit_descriptor *desc) { int mu_channels; - void *c;
if (desc->bLength < sizeof(*desc)) return -EINVAL; @@ -762,13 +761,6 @@ static int uac_mixer_unit_get_channels(s break; }
- if (!mu_channels) - return 0; - - c = uac_mixer_unit_bmControls(desc, state->mixer->protocol); - if (c - (void *)desc + (mu_channels - 1) / 8 >= desc->bLength) - return 0; /* no bmControls -> skip */ - return mu_channels; }
@@ -2009,6 +2001,31 @@ static int parse_audio_feature_unit(stru * Mixer Unit */
+/* check whether the given in/out overflows bmMixerControls matrix */ +static bool mixer_bitmap_overflow(struct uac_mixer_unit_descriptor *desc, + int protocol, int num_ins, int num_outs) +{ + u8 *hdr = (u8 *)desc; + u8 *c = uac_mixer_unit_bmControls(desc, protocol); + size_t rest; /* remaining bytes after bmMixerControls */ + + switch (protocol) { + case UAC_VERSION_1: + default: + rest = 1; /* iMixer */ + break; + case UAC_VERSION_2: + rest = 2; /* bmControls + iMixer */ + break; + case UAC_VERSION_3: + rest = 6; /* bmControls + wMixerDescrStr */ + break; + } + + /* overflow? */ + return c + (num_ins * num_outs + 7) / 8 + rest > hdr + hdr[0]; +} + /* * build a mixer unit control * @@ -2137,6 +2154,9 @@ static int parse_audio_mixer_unit(struct if (err < 0) return err; num_ins += iterm.channels; + if (mixer_bitmap_overflow(desc, state->mixer->protocol, + num_ins, num_outs)) + break; for (; ich < num_ins; ich++) { int och, ich_has_controls = 0;