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[128.210.107.27]) by smtp.googlemail.com with ESMTPSA id f1sm19353759ioh.73.2019.08.19.15.00.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Aug 2019 15:00:41 -0700 (PDT) From: Hui Peng To: security@kernel.org Cc: Hui Peng , Mathias Payer , Jaroslav Kysela , Takashi Iwai , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Subject: [PATCH] Fix an OOB bug in uac_mixer_unit_bmControls Date: Mon, 19 Aug 2019 18:00:04 -0400 Message-Id: <20190819220005.10178-1-benquike@gmail.com> X-Mailer: git-send-email 2.22.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org `uac_mixer_unit_get_channels` calls `uac_mixer_unit_bmControls` to get pointer to bmControls field. The current implementation of `uac_mixer_unit_get_channels` does properly check the size of uac_mixer_unit_descriptor descriptor and may allow OOB access in `uac_mixer_unit_bmControls`. Reported-by: Hui Peng Reported-by: Mathias Payer Signed-off-by: Hui Peng --- sound/usb/mixer.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index b5927c3d5bc0..00e6274a63c3 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -738,28 +738,39 @@ static int get_cluster_channels_v3(struct mixer_build *state, unsigned int clust static int uac_mixer_unit_get_channels(struct mixer_build *state, struct uac_mixer_unit_descriptor *desc) { - int mu_channels; + int mu_channels = 0; void *c; - if (desc->bLength < sizeof(*desc)) - return -EINVAL; if (!desc->bNrInPins) return -EINVAL; - if (desc->bLength < sizeof(*desc) + desc->bNrInPins) - return -EINVAL; switch (state->mixer->protocol) { case UAC_VERSION_1: + // limit derived from uac_mixer_unit_bmControls + if (desc->bLength < sizeof(*desc) + desc->bNrInPins + 4) + return 0; + + mu_channels = uac_mixer_unit_bNrChannels(desc); + break; + case UAC_VERSION_2: - default: - if (desc->bLength < sizeof(*desc) + desc->bNrInPins + 1) + // limit derived from uac_mixer_unit_bmControls + if (desc->bLength < sizeof(*desc) + desc->bNrInPins + 6) return 0; /* no bmControls -> skip */ + mu_channels = uac_mixer_unit_bNrChannels(desc); break; case UAC_VERSION_3: + // limit derived from uac_mixer_unit_bmControls + if (desc->bLength < sizeof(*desc) + desc->bNrInPins + 2) + return 0; /* no bmControls -> skip */ + mu_channels = get_cluster_channels_v3(state, uac3_mixer_unit_wClusterDescrID(desc)); break; + + default: + break; } if (!mu_channels) -- 2.22.1