From patchwork Fri Feb 28 13:46:57 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Nikita Zhandarovich X-Patchwork-Id: 13996447 X-Patchwork-Delegate: johannes@sipsolutions.net Received: from exchange.fintech.ru (exchange.fintech.ru [195.54.195.159]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4E4BC14F70; Fri, 28 Feb 2025 13:47:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.54.195.159 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740750428; cv=none; b=YjwCxytv0DbOGUFXTTGy+ubxC3Uova7h7VuLpe/EjzNa41LGdAupFXKdn49lw4NjpNDGjQGzWk5PIuEnbzYrWX45J+t+kxMEO7Q4rwDn6JXcW+7G/6sBfNWVBV8fgMNveXTjzfbypCdff6MrPjfszVkMNxWKE+s1h7bmHD6lpKA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740750428; c=relaxed/simple; bh=vPa7bRHI2f735gWDrnnELJCYcr7u91wOFCCK9+KiE3s=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=rjVShbvLt7LRJLwg02zWqy1akTlTLImby9kRgqafsw4XstkffuX6RsOMU2zAbnJOA8VIDlg4o4sLaGtGUjJQdpauGLZydx5Ifb6SyOX0ZLABzXqkM98bNMRR14nUOAQXZGjDhN6jBnNboYiaVMGI4PESuq/4XgtbpvHQfXY+cas= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fintech.ru; spf=pass smtp.mailfrom=fintech.ru; arc=none smtp.client-ip=195.54.195.159 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fintech.ru Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fintech.ru Received: from Ex16-01.fintech.ru (10.0.10.18) by exchange.fintech.ru (195.54.195.169) with Microsoft SMTP Server (TLS) id 14.3.498.0; Fri, 28 Feb 2025 16:47:00 +0300 Received: from localhost (10.0.253.138) by Ex16-01.fintech.ru (10.0.10.18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2242.4; Fri, 28 Feb 2025 16:47:00 +0300 From: Nikita Zhandarovich To: Johannes Berg CC: Nikita Zhandarovich , "Luis R. Rodriguez" , "John W. Linville" , , , , , Subject: [PATCH] cfg80211: regulatory: improve invalid hints checking Date: Fri, 28 Feb 2025 16:46:57 +0300 Message-ID: <20250228134659.1577656-1-n.zhandarovich@fintech.ru> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: Ex16-02.fintech.ru (10.0.10.19) To Ex16-01.fintech.ru (10.0.10.18) Syzbot keeps reporting an issue [1] that occurs when erroneous symbols sent from userspace get through into user_alpha2[] via regulatory_hint_user() call. Such invalid regulatory hints should be rejected. While a sanity check from commit 47caf685a685 ("cfg80211: regulatory: reject invalid hints") looks to be enough to deter these very cases, there is a way to get around it due to 2 reasons. 1) The way isalpha() works, symbols other than latin lower and upper letters may be used to determine a country/domain. For instance, greek letters will also be considered upper/lower letters and for such characters isalpha() will return true as well. However, ISO-3166-1 alpha2 codes should only hold latin characters. 2) While processing a user regulatory request, between reg_process_hint_user() and regulatory_hint_user() there happens to be a call to queue_regulatory_request() which modifies letters in request->alpha2[] with toupper(). This works fine for latin symbols, less so for weird letter characters from the second part of _ctype[]. Syzbot triggers a warning in is_user_regdom_saved() by first sending over an unexpected non-latin letter that gets malformed by toupper() into a character that ends up failing isalpha() check. Prevent this by enhancing is_an_alpha2() to ensure that incoming symbols are latin letters and nothing else. [1] Syzbot report: ------------[ cut here ]------------ Unexpected user alpha2: A� WARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 is_user_regdom_saved net/wireless/reg.c:440 [inline] WARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_alpha2 net/wireless/reg.c:3424 [inline] WARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516 Modules linked in: CPU: 1 UID: 0 PID: 964 Comm: kworker/1:2 Not tainted 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events_power_efficient crda_timeout_work RIP: 0010:is_user_regdom_saved net/wireless/reg.c:440 [inline] RIP: 0010:restore_alpha2 net/wireless/reg.c:3424 [inline] RIP: 0010:restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516 ... Call Trace: crda_timeout_work+0x27/0x50 net/wireless/reg.c:542 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f2/0x390 kernel/kthread.c:389 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Reported-by: syzbot+e10709ac3c44f3d4e800@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=e10709ac3c44f3d4e800 Fixes: 09d989d179d0 ("cfg80211: add regulatory hint disconnect support") Cc: stable@kernel.org Signed-off-by: Nikita Zhandarovich --- P.S. Apologies to Johannes Berg for sending the first patch iteration in a wrong way. net/wireless/reg.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/wireless/reg.c b/net/wireless/reg.c index 2dd0533e7660..212e9561aae7 100644 --- a/net/wireless/reg.c +++ b/net/wireless/reg.c @@ -407,7 +407,8 @@ static bool is_an_alpha2(const char *alpha2) { if (!alpha2) return false; - return isalpha(alpha2[0]) && isalpha(alpha2[1]); + return isascii(alpha2[0]) && isalpha(alpha2[0]) && + isascii(alpha2[1]) && isalpha(alpha2[1]); } static bool alpha2_equal(const char *alpha2_x, const char *alpha2_y)