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 8657241A4E2 for ; Tue, 22 Sep 2026 08:24:49 +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=1790065490; cv=none; b=cejtBIwNqSFV8EK1iLWqiuPlhbW+cc7ynsTIwnHrn1SK4BQVA4w9wptWTUflM0yFXb+5fiktRDDWXJs0jrAsNpcO7nYVtuvaOjCG0nVHriaH+ofRx5tuA4C0MgPHLRv01KwXNOf/TdvGGxNj3CSIdrrxG5HhzzP2tCZOikFR/p0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790065490; c=relaxed/simple; bh=MS4El0R8AG8atWKJq0bPRReWpsbAv8hM0YFC/HYJsnA=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=bNnjbmGtiIoICAtFNUA2Vb5gQkQHUEjI6FpuZc0C1RKCzXbAGWQcnL1EozeA9uurWGwsymVVsOAe3vPUREXa1wTbuHqh059Q0zY12yL1vVZVuiQnj3fpLVdqVHfWpAky5ixDh+Fqx3fdnkLkGvUZsrOB0x8dMyl7znuCB8iqvW8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=U7fiebic; 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="U7fiebic" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 702361F000FF; Tue, 22 Sep 2026 08:24:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790065489; bh=LBFceQk/PVQfbwrb8GGNx0Ok92XoE3L4MQWJfiPHfIQ=; h=Subject:To:Cc:From:Date; b=U7fiebic5hAit4nnEXUfb/VNg1UbTvD7c4HaPHynICcFtJJpUYv1Y6qryU+YPKFwm ksom3d6pUKcXyqFnmC8NmcfrqJ93rCU5tmR0Llrq+pmdVRWy0AHvYhxBbdGDjUuTPx bq3jxo470OVMwyOBrTueElgPmoiOjh/K8/FRpLAE= Subject: FAILED: patch "[PATCH] ALSA: usb-audio: Clamp implicit feedback packet count to URB" failed to apply to 6.18-stable tree To: xmei5@asu.edu,tiwai@suse.de Cc: From: Date: Tue, 22 Sep 2026 10:24:45 +0200 Message-ID: <2026092245-renewably-elevate-ca0d@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x 76a986c980bb502c7688d605ac7a67fd257a9a1b # git commit -s git send-email --to '' --in-reply-to '2026092245-renewably-elevate-ca0d@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 76a986c980bb502c7688d605ac7a67fd257a9a1b Mon Sep 17 00:00:00 2001 From: Xiang Mei Date: Sat, 12 Sep 2026 13:05:30 -0700 Subject: [PATCH] ALSA: usb-audio: Clamp implicit feedback packet count to URB capacity 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 diff --git a/sound/usb/card.h b/sound/usb/card.h index e34d92d576a2..8299ac241c60 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 0835943d7b0e..b72ce1e9bfb1 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -492,9 +492,10 @@ 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 */ @@ -1242,15 +1243,16 @@ 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)