From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794361600; b=n3NfydcbvNO1qBAvMQeDqxvNUfgBq0kwFNUyey3mAE6TOYBul/fOAHgOtMv7oN8HeXWv bVx5hYUZ1iHiph2/CbnWCwqKIDsJVUqEeRAFr4QyM4Xr4B6pfpfz4OzEm1MQTPeppIweo oSp12qzfgYXSQJrQCuYoMEeJ+w8UeyjuFr0eR6VOL4uoKlnvXv93r/es6Vki0uKLeUref WHHv5nhU7e6ZmK8ZavSmIRZKuEYQ+bTLM5dIAX0ZZfP8p7l+r6qaQiTxbUZ5omRKhs0Ob pqI6AnA+8hQjDbYaF44Rco7aDDilzLyEYg+v4ZKK1tv3Xise/Y8607xGrctg+wcVDvg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794361600; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=j/BVaAtuz6oclaydxQCp66AyhXmrhiWBoThGvvx7Z1I=; b=Pwudae4GjCqjiBlPCOc6swIY+IsJ8B9f9DJLhiNxo8TdkqBiMs6s6VWR2V5VnHtVQ9Ny pgOQD+pl1jc/miqu2TJrt299i7HBJIlf/Aaimy3FEX/8hKQyCfIyf+nPCl1iD0Ez9jh2t dtLsklXR+Ac2cs2os+G66HD43+cL+saiNn0TjI94sKDUchuShF55jbxutGli17xJwh+/b XXQbrlGd1SqyDXZxReuCnEGXO9FJZw+FXdSmz6GA9cIwnt5SUcjYX8ogIWYp7q9Z9wR+m bN3uCzlx00p9T8esVwyY0HSLOjm7xe6xkawgJq4YqV1nibuczXD6YLBTV14EkHH3akQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=mFVUYRNn; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F881606A31C for ; Wed, 11 Nov 2026 01:46:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=mFVUYRNn Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D24A1F0089F; Wed, 11 Nov 2026 01:46:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794361600; bh=j/BVaAtuz6oclaydxQCp66AyhXmrhiWBoThGvvx7Z1I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mFVUYRNnaYqgk9mSZkcBfnOrkMdkAvpbDzsG7ulfMBGD/iXZya3duMYhHfwmXJJuX b66jVgmnLMDAZB7tuzmL1hHR5wesEtstAvCjPWZDhtdD3Hvj/zHDtUKJe/4KGq3BvS QYkKpGBHc7HgLY3hiWtR4EEZDPfmyMOisVh51G2nS1UiaC++PfMTokr0d9cTKh8ewu j95g7J73Fh6CnibZyOZd7irHQcZTeVIk3g3GmTXwc914N8o0POuaWI2aMXZNimultE LA2xy6pSD+WD2Bya+t17vCVuxIoX5bdJv/kq7vwu4sMTa+RChior/edNsJMTzyfScn g25cO7G6W0PoQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Michal Pecio , co+fd80bc5967eb22c3@bugs.sh, Mathias Nyman , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 6.12.y] usb: xhci: Fix bounce buffer overflow Date: Tue, 10 Nov 2026 20:46:38 -0500 Message-ID: <20261111014521.406533-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107052104-failed-6.12-68c5cb7574c5@kernel.org> References: <20261107052104-failed-6.12-68c5cb7574c5@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Michal Pecio [ Upstream commit 68c5cb7574c567e83ba95258cb146db95e069a87 ] High-speed devices with out of spec 1024 byte bulk endpoints exist and are allowed by USB core, but xhci-hcd always sets packet size to 512. The exact nature of these devices isn't documented, commit fb5ee84ea72c ("USB: Accept bulk endpoints with 1024-byte maxpacket") only states that they "don't work with xHCI host controllers", whatever it means. But somebody (or a malicious device) can try, and then the driver will allocate a 512 byte bounce buffer for this endpoint and may write up to 1024 bytes into it if particular scatter-gather URBs are used, because xhci_align_td() obtains packet size from the descriptor. Fix this. As a side effect, TRBs will be aligned to the packet size chosen by the driver on all endpoints of all speeds. Alignment serves the xHC, not device, so this is fine. Only out of spec devices are affected anyway. Reported-by: co+fd80bc5967eb22c3@bugs.sh Link: https://lore.kernel.org/linux-usb/D4tcSGerkYkIV1DmaUo1t8TaR5qQElDLkidn@bugs.sh/ Fixes: f9c589e142d0 ("xhci: TD-fragment, align the unsplittable case with a bounce buffer") Cc: stable@vger.kernel.org Signed-off-by: Michal Pecio Signed-off-by: Mathias Nyman Link: https://patch.msgid.link/20261009151624.618967-11-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman [ sashal: Removed usb_endpoint_maxp() instead of xhci_usb_endpoint_maxp() in xhci_align_td(). ] Signed-off-by: Sasha Levin --- drivers/usb/host/xhci-ring.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 597a9a8c16b9f..2c35cb444f737 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -3583,15 +3583,13 @@ static u32 xhci_td_remainder(struct xhci_hcd *xhci, int transferred, static int xhci_align_td(struct xhci_hcd *xhci, struct urb *urb, u32 enqd_len, - u32 *trb_buff_len, struct xhci_segment *seg) + u32 *trb_buff_len, struct xhci_segment *seg, u32 max_pkt) { struct device *dev = xhci_to_hcd(xhci)->self.sysdev; unsigned int unalign; - unsigned int max_pkt; u32 new_buff_len; size_t len; - max_pkt = usb_endpoint_maxp(&urb->ep->desc); unalign = (enqd_len + *trb_buff_len) % max_pkt; /* we got lucky, last normal TRB data on segment is packet aligned */ @@ -3736,9 +3734,8 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags, if (enqd_len + trb_buff_len < full_len) { field |= TRB_CHAIN; if (trb_is_link(ring->enqueue + 1)) { - if (xhci_align_td(xhci, urb, enqd_len, - &trb_buff_len, - ring->enq_seg)) { + if (xhci_align_td(xhci, urb, enqd_len, &trb_buff_len, + ring->enq_seg, ring->bounce_buf_len)) { send_addr = ring->enq_seg->bounce_dma; /* TD bounced at least, and last on this seg */ td->bounce_seg = ring->enq_seg; -- 2.53.0