4.20-stable review patch. If anyone has any objections, please let me know.
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From: Takashi Iwai tiwai@suse.de
commit 0bfe5e434e6665b3590575ec3c5e4f86a1ce51c9 upstream.
We've had some sanity checks of the mixer unit descriptors but they are too loose and some corner cases are overlooked. Add more strict checks in uac_mixer_unit_get_channels() for avoiding possible OOB accesses by malformed descriptors.
This also changes the semantics of uac_mixer_unit_get_channels() slightly. Now it returns zero for the cases where the descriptor lacks of bmControls instead of -EINVAL. Then the caller side skips the mixer creation for such unit while it keeps parsing it. This corresponds to the case like Maya44.
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 | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)
--- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -753,8 +753,9 @@ static int uac_mixer_unit_get_channels(s struct uac_mixer_unit_descriptor *desc) { int mu_channels; + void *c;
- if (desc->bLength < 11) + if (desc->bLength < sizeof(*desc)) return -EINVAL; if (!desc->bNrInPins) return -EINVAL; @@ -763,6 +764,8 @@ static int uac_mixer_unit_get_channels(s case UAC_VERSION_1: case UAC_VERSION_2: default: + if (desc->bLength < sizeof(*desc) + desc->bNrInPins + 1) + return 0; /* no bmControls -> skip */ mu_channels = uac_mixer_unit_bNrChannels(desc); break; case UAC_VERSION_3: @@ -772,7 +775,11 @@ static int uac_mixer_unit_get_channels(s }
if (!mu_channels) - return -EINVAL; + 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; } @@ -944,7 +951,7 @@ static int check_input_term(struct mixer struct uac_mixer_unit_descriptor *d = p1;
err = uac_mixer_unit_get_channels(state, d); - if (err < 0) + if (err <= 0) return err;
term->channels = err; @@ -2118,7 +2125,7 @@ static int parse_audio_mixer_unit(struct if (err < 0) continue; /* no bmControls field (e.g. Maya44) -> ignore */ - if (desc->bLength <= 10 + input_pins) + if (!num_outs) continue; err = check_input_term(state, desc->baSourceID[pin], &iterm); if (err < 0)