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 990CF368D40; Tue, 21 Jul 2026 19:28:31 +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=1784662112; cv=none; b=p2pwf/8lfhHKxbkki/2qui0AaxEBA8Qfkxks8xYubSfacqYv6dXuGmwFiSvZfLfDiJSq0i+e4b+S+sL72eKTcL/EgE/CvYb8cwWvxlCgiYy8PjSfvCKgN2YK/hhWZDbqQ6ZFkrGTf9JcNbaKmVVUekCPoBAp1gVnsYIY/yDRe7E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784662112; c=relaxed/simple; bh=GGzHSKlPR2vwWUXFOoGs6WEIc8cdJkwwo21HUZ6cKhU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=K1rGsrIb4pZ5PDJ1daCTnXB29qKYnX1I3uLrxkkoNwoj3/D5K42aRvkWU5nTYdqiwocrqrt259w4lTsOxoalJhOiakYaCm/d7xbslK9FA71W4K2+Mm0Fis/Ds24e3QJgmz2bQwXHQoQg1CJsInD5RtJuGEy5iLXL8rOm49H6gs4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=icNL6rGT; 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="icNL6rGT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BCE9F1F00A3A; Tue, 21 Jul 2026 19:28:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784662111; bh=Rjg4R6+WN4D1BBp1ddTS/fF3fAGxnS7MBf5W/5YUQa4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=icNL6rGTKTOSs4wKk7zI4FP2Q8KURsinYd2nuG50Xdp1EV6h/ABxFzD/qCpi9lqeB 8Qj+MJmdMW9LKXhvkG902gP52Jey9GRDqMliMPNGKgy8A2s+mzgRT+G0Y694LkrHnw mlkj/y7U36/H/DJuah8OBijqUb3NqjPs/TqMgg3s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xiang Mei , Weiming Shi , Luiz Augusto von Dentz , Sasha Levin Subject: [PATCH 6.12 0319/1276] Bluetooth: eir: Fix stack OOB write when prepending the Flags AD Date: Tue, 21 Jul 2026 17:12:42 +0200 Message-ID: <20260721152453.236161655@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152446.065700225@linuxfoundation.org> References: <20260721152446.065700225@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Weiming Shi [ Upstream commit 6f5fb689fdf80bdd143f22a502f9eb1f3c85e286 ] eir_create_adv_data() builds the advertising data into a fixed-size buffer ("size", 31 for the legacy path). It may prepend a 3-byte "Flags" AD structure (LE_AD_NO_BREDR on an LE-only controller) and then copies the per-instance data without checking that it still fits: memcpy(ptr, adv->adv_data, adv->adv_data_len); tlv_data_max_len() only reserves those 3 bytes when the user-supplied flags carry a managed-flags bit, so an instance added with flags == 0 is accepted with adv_data_len up to the full buffer. At advertise time the flags are still prepended, and the memcpy() writes 3 + adv_data_len bytes into the size-byte buffer: BUG: KASAN: stack-out-of-bounds in eir_create_adv_data (net/bluetooth/eir.c:301) Write of size 31 at addr ffff88800a547bdc by task kworker/u9:0/65 Workqueue: hci0 hci_cmd_sync_work __asan_memcpy (mm/kasan/shadow.c:106) eir_create_adv_data (net/bluetooth/eir.c:301) hci_update_adv_data_sync (net/bluetooth/hci_sync.c:1310) hci_schedule_adv_instance_sync (net/bluetooth/hci_sync.c:1817) hci_cmd_sync_work (net/bluetooth/hci_sync.c:332) This frame has 1 object: [32, 64) 'cp' The "Flags" structure is added by the kernel, not requested by userspace, so only prepend it when it fits together with the instance advertising data; when there is no room for both, drop the flags rather than the user-provided data. Reachable by a local user with CAP_NET_ADMIN owning an LE-only controller on the legacy advertising path. Fixes: b44133ff03be ("Bluetooth: Support the "discoverable" adv flag") Reported-by: Xiang Mei Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Weiming Shi Reported-by: Xiang Mei Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- net/bluetooth/eir.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/bluetooth/eir.c b/net/bluetooth/eir.c index 3f72111ba651f9..1de5f9df6eec00 100644 --- a/net/bluetooth/eir.c +++ b/net/bluetooth/eir.c @@ -283,10 +283,12 @@ u8 eir_create_adv_data(struct hci_dev *hdev, u8 instance, u8 *ptr, u8 size) if (!flags) flags |= mgmt_get_adv_discov_flags(hdev); - /* If flags would still be empty, then there is no need to - * include the "Flags" AD field". + /* Only add the "Flags" if it fits together with the instance + * advertising data; drop it rather than overflow the buffer. */ - if (flags && (ad_len + eir_precalc_len(1) <= size)) { + if (flags && + (ad_len + eir_precalc_len(1) + + (adv ? adv->adv_data_len : 0) <= size)) { ptr[0] = 0x02; ptr[1] = EIR_FLAGS; ptr[2] = flags; -- 2.53.0