From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9998352E055; Mon, 31 Aug 2026 13:44:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183890; cv=none; b=Qvj1mJN49YO7xAJNQuhz32WBTpNgOr1y990N9BYeLGecwx84lWTozAmG50hMDWuhZY6SbqdB/4C3DaEAQi9Sc525b47a/4wpHuIRWnd7cxobf8KgMF0BQSTrkD3eYccaZWvONg8kAcUQ+00ALJrCSPITT/A+AvaBGrkXPT2zi20= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183890; c=relaxed/simple; bh=DbQFXFAIlpYKtYjrAzEPNukv2yIRqLCvEUOVF0qDQXw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=I6XAYmoyZxV/SrDsT0PmzIivhssYj/OjTtV4oxG331gvJX1w2x3KLfTD8pLa4qjNyn7xkFYBsGBB7E/Q/Eck1hGGsfBuOEPJVJxw20oGZuFTx66coEe3zx0pr3AY6LoU7Bi9xbJAkU4dbPe3JnEhksxMMWL7P0j+xFPqFMNNSQk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xNyiKgib; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xNyiKgib" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 683D31F00A3D; Mon, 31 Aug 2026 13:44:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788183888; bh=r18u8tw9lybLkAczU2oe03cvpenlorLHnLh8S3KVuyE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=xNyiKgib923XT5qLJF6jjV2z/hzdGVk0piKhT/qG5RxAyt3uL4Gt3oNjfOYvxzE8D qXcECd729E0mmNXEyEgMPS4EBt+YsF0/H2hjmKZAcrzH0aRlgZM3y731y6p50E41lh f1DQaaDJDQp0LgwtMhNZs6zPwW8CWzk2yT/lQLz4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Marouane El Moufid , Takashi Iwai Subject: [PATCH 7.1 70/76] ALSA: usb-audio: fix OOB write in snd_usbmidi_novation_output() Date: Mon, 31 Aug 2026 15:34:42 +0200 Message-ID: <20260831133403.036816842@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260831133359.185608553@linuxfoundation.org> References: <20260831133359.185608553@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marouane El Moufid commit 1035a8f63bae28e498b0e7b5ac91d749844a7158 upstream. snd_usbmidi_novation_output() lays out a two-byte header at transfer_buffer[0..1] and passes &transfer_buffer[2] together with a length of ep->max_transfer - 2 to snd_rawmidi_transmit(): count = snd_rawmidi_transmit(ep->ports[0].substream, &transfer_buffer[2], ep->max_transfer - 2); ep->max_transfer comes from the output endpoint's wMaxPacketSize via usb_maxpacket(). A malformed or malicious device can advertise a bulk OUT endpoint with a wMaxPacketSize of 1 - the USB core only clamps this value downwards - so ep->max_transfer becomes 1 and the count argument becomes -1. snd_rawmidi_transmit() passes the negative count on to __snd_rawmidi_transmit_peek(), where "if (count1 > count) count1 = count" leaves count1 negative; get_aligned_size() keeps it negative for a byte-stream substream, so the following memcpy(buffer, ..., count1) runs with a (size_t)-1 length and writes far past the transfer buffer, which was allocated with usb_alloc_coherent(ep->max_transfer). This is the same class of bug that was fixed for snd_usbmidi_akai_output() in commit 0970274613fb ("ALSA: usb-audio: fix OOB write in snd_usbmidi_akai_output()"); the novation output routine was left unguarded. Bail out when the endpoint cannot hold the two-byte header plus at least one payload byte. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Marouane El Moufid Link: https://patch.msgid.link/178749334830.543645.13722252148340572274@espilon.net Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/usb/midi.c | 2 ++ 1 file changed, 2 insertions(+) --- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -875,6 +875,8 @@ static void snd_usbmidi_novation_output( if (!ep->ports[0].active) return; + if (ep->max_transfer < 3) + return; transfer_buffer = urb->transfer_buffer; count = snd_rawmidi_transmit(ep->ports[0].substream, &transfer_buffer[2],