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 D57D4542EFE for ; Tue, 22 Sep 2026 12:19:18 +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=1790079560; cv=none; b=a3Bts1tL0eWmlQML74NyfujGUln4HBrDhSUrdoaKwRpIriLMJhTtnPCwSEoD3tV4GUaIkQ62gsjc3/lQpaDmGJhfx0mBOj/ueikLrFW0tgJniyiSOeJP+78Mcw8ExnCIlFVGNh3vRlHX4GTZfBDnQMQHZnnHYns1pkdOlZfEPXg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790079560; c=relaxed/simple; bh=KDkH4AtZ3pH4GEGTNNw0i/rLdnwRXKJjASamVJmzxXM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZqsiXxZExinlcelCJxL9SKzgWb5n2wRlRtit/ZJgKCCQn33e8eO3Ts8j50H1oF+FcmpPBXLUFypbBa/mJ4iAeHvioVLhRXGTLBdOXVMqxOZMino5BEgYUdC4lawJRC882nifS2hoYQRQsgW4Q2Psq0fwp19B4RddH24zAoTrQjM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UuuVtt/H; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UuuVtt/H" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0C3771F0089A; Tue, 22 Sep 2026 12:19:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790079558; bh=1PQPFAKaEnXzWhY74QLRxXGs/rXH69xKNWNoDnevM8o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UuuVtt/HM8MpbfbQTm/wiJKqMnoxRsLaqzHWOh4qWv9LpbA0BbCIYa9nyNNaVSD1H HyktmTWQXsTysTHf4KP2mYeBJKIGpjP2YYuHHKZG7UdagSSzTIUTOENZeWkfEy9zMQ afDDvjMGMHS149OGSo7LSgCZQhZIj3Ek238Aapw4WVxBTOiTQEMibJ2K16I/XvKchA 9YgZwn0LnaeX70qvUWVNOfsZNMXjlvmglm31nKNnfP7tVb8AmdmxrhEVvDJetzy1KN 7E8D45Gfg0xUFHr8Batio5Yk+TWQhgSR/2vZhC4sadEgMrB6iTEdZSFpfI762OLitC OKKSMfSTLJeAA== From: Sasha Levin To: stable@vger.kernel.org Cc: Xiang Mei , co+8eacd4fa193b1b28@bugs.sh, Takashi Iwai , Sasha Levin Subject: [PATCH 6.18.y 2/2] ALSA: usb-audio: Clamp implicit feedback packet count to URB capacity Date: Tue, 22 Sep 2026 08:19:15 -0400 Message-ID: <20260922121915.2213648-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260922121915.2213648-1-sashal@kernel.org> References: <2026092245-renewably-elevate-ca0d@gregkh> <20260922121915.2213648-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Xiang Mei [ Upstream commit 76a986c980bb502c7688d605ac7a67fd257a9a1b ] data_ep_set_params() allocates each data URB for exactly u->packets isochronous frames, so urb->iso_frame_desc[] has u->packets slots and ctx->packets is the driver's only record of that limit. For an implicit feedback sink, snd_usb_queue_pending_output_urbs() overwrites it with the sync source's packet count, which is calculated independently from the capture endpoint's parameters. When that count is larger, prepare_playback_urb() and prepare_silent_urb() can write iso_frame_desc[] past the allocation; their existing bounds limit payload bytes, not the descriptor index. The reproducer uses a high-speed UAC2 device declaring bInterval 1 for implicit feedback capture (8 packets) and bInterval 4 for playback (1 packet). On the first capture completion after the stream starts, it accesses seven descriptors spanning 112 bytes beyond the one-packet URB: BUG: KASAN: slab-out-of-bounds in prepare_playback_urb (sound/usb/pcm.c:1560) Write of size 4 at addr ffff88801e696ad0 by task vhci_rx/178 prepare_playback_urb (sound/usb/pcm.c:1560) prepare_outbound_urb (sound/usb/endpoint.c:340) snd_usb_queue_pending_output_urbs (sound/usb/endpoint.c:501) snd_complete_urb (sound/usb/endpoint.c:1834) __usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1657) usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1741) vhci_rx_loop (drivers/usb/usbip/vhci_rx.c:107) kthread (kernel/kthread.c:436) The buggy address belongs to the object at ffff88801e696a00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 0 bytes to the right of allocated 208-byte region [ffff88801e696a00, ffff88801e696ad0) Record the allocated packet count per endpoint and clamp both the adopted count and the packet-size copy to it. Fold the Format Type II delimiter into urb_packs before the allocation loop so the recorded limit matches every URB. Fixes: cf044e441902 ("ALSA: usb-audio: Update the number of packets properly at receiving") Reported-by: co+8eacd4fa193b1b28@bugs.sh Closes: https://lore.kernel.org/all/22xPn8drvIUtYgVeQnBiNqXuevOTpBAjepLz%40bugs.sh/ Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-5 Signed-off-by: Xiang Mei Link: https://patch.msgid.link/20260912200530.1955491-1-xmei5@asu.edu Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/usb/card.h | 1 + sound/usb/endpoint.c | 12 +++++++----- 2 files changed, 8 insertions(+), 5 deletions(-) diff --git a/sound/usb/card.h b/sound/usb/card.h index e34d92d576a27..8299ac241c603 100644 --- a/sound/usb/card.h +++ b/sound/usb/card.h @@ -116,6 +116,7 @@ struct snd_usb_endpoint { unsigned int phase; /* phase accumulator */ unsigned int maxpacksize; /* max packet size in bytes */ unsigned int maxframesize; /* max packet size in frames */ + unsigned int max_urb_packs; /* packets allocated per data URB */ unsigned int max_urb_frames; /* max URB size in frames */ unsigned int curpacksize; /* current packet size in bytes (for capture) */ unsigned int curframesize; /* current packet size in frames (for capture) */ diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index 3f46b82561966..b0202ae44b967 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -489,9 +489,10 @@ int snd_usb_queue_pending_output_urbs(struct snd_usb_endpoint *ep, /* copy over the length information */ if (implicit_fb) { - ctx->packets = packet->packets; + ctx->packets = min_t(int, packet->packets, + ep->max_urb_packs); memcpy(ctx->packet_size, packet->packet_size, - packet->packets * sizeof(packet->packet_size[0])); + ctx->packets * sizeof(packet->packet_size[0])); } /* call the data handler to fill in playback data */ @@ -1235,15 +1236,16 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep) ep->nurbs = min(max_urbs, urbs_per_period * ep->cur_buffer_periods); } + if (fmt->fmt_type == UAC_FORMAT_TYPE_II) + urb_packs++; /* for transfer delimiter */ + ep->max_urb_packs = urb_packs; + /* allocate and initialize data urbs */ for (i = 0; i < ep->nurbs; i++) { struct snd_urb_ctx *u = &ep->urb[i]; u->index = i; u->ep = ep; u->packets = urb_packs; - - if (fmt->fmt_type == UAC_FORMAT_TYPE_II) - u->packets++; /* for transfer delimiter */ u->buffer_size = maxsize * u->packets; u->urb = usb_alloc_urb(u->packets, GFP_KERNEL); if (!u->urb) -- 2.53.0