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 341833D955A; Thu, 2 Jul 2026 16:23:23 +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=1783009406; cv=none; b=bw08hVpa4J6MDY9+0BNmoRpC52iGkW/C+HpN3iz5WDkcNBG3xl+wO3wtZL3CSYpPIefdCBZc7GhLazIqQfJPwAX8EswKF7+0o/ERtU6yR1OuetDEETmnrN3FlxbXFNxFnOBc55dvezcXtGz/47w6Az5qyynqf2heYQU3nteaXcU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783009406; c=relaxed/simple; bh=74b/PoJ5vIJnEsfDGgV8bf3NLDVOGrAE15PX2gkxAx4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lYUiwUZu3aJvORI5Fr1axWVVpHuy/XUerFp+eL2GBGAyQoVs38yqk8uEA1KEyc5oCxpadfcDWmaGCL0r3fu0EVEsMTAby+k+WhOHZBlUV3ZKLO6K9OrqEm4X9VLwihZrfH8iqhrVbIQDXL1gOjuFrCSs3O6Kew9f1zfYsqZRAI8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=UyUoEHEp; 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="UyUoEHEp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EFF51F00A3F; Thu, 2 Jul 2026 16:23:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783009403; bh=2CBPvcVJY5qXJneL+9xgEjvXSdfCmbeIuDFLFr9J9Go=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UyUoEHEpDin/X9k9IKL2Hl7wcC1GA/ITwEOIiJAkinr7ab/eKjSzhTU0jpEJAYw7r 6jl9/GJYB+fb1QsxQvxuMvwBa8sezSex3EfGWXlaWJbcJWP/pJwJu8sMI4zt9kVfC2 Sw9eZrmS1kuZTNC42iZx89xdo/a6LMnCXXbaY+x8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, Sven Eckelmann , Sasha Levin Subject: [PATCH 5.10 37/96] batman-adv: tp_meter: avoid window underflow Date: Thu, 2 Jul 2026 18:19:29 +0200 Message-ID: <20260702155109.766219927@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155108.949633242@linuxfoundation.org> References: <20260702155108.949633242@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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sven Eckelmann commit 765947b81fb54b6ebb0bc1cfe55c0fa399e002b8 upstream. In batadv_tp_avail(), win_left is calculated with 32-bit unsigned arithmetic: win_left = win_limit - tp_vars->last_sent; During Fast Recovery, cwnd is inflated and last_sent advances rapidly. When Fast Recovery ends, cwnd drops abruptly back to ss_threshold. If the newly shrunk win_limit is less than last_sent, the unsigned subtraction will underflow, wrapping to a massive positive value. Instead of returning that the window is full (unavailable), it returns that the sender can continue sending. To handle this situation, it must be checked whether the windows end sequence number (win_limit) has to be compared with the last sent sequence number. If it would be before the last sent sequence number, then more acks are needed before the transmission can be started again. Cc: stable@kernel.org Fixes: 33a3bb4a3345 ("batman-adv: throughput meter implementation") Signed-off-by: Sven Eckelmann Signed-off-by: Sasha Levin --- net/batman-adv/tp_meter.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c index d8ad58ccef2608..10953096996ab1 100644 --- a/net/batman-adv/tp_meter.c +++ b/net/batman-adv/tp_meter.c @@ -825,10 +825,15 @@ static void batadv_tp_recv_ack(struct batadv_priv *bat_priv, static bool batadv_tp_avail(struct batadv_tp_vars *tp_vars, size_t payload_len) { + u32 last_sent = READ_ONCE(tp_vars->last_sent); u32 win_left, win_limit; win_limit = atomic_read(&tp_vars->last_acked) + tp_vars->cwnd; - win_left = win_limit - tp_vars->last_sent; + + if (batadv_seq_before(last_sent, win_limit)) + win_left = win_limit - last_sent; + else + win_left = 0; return win_left >= payload_len; } -- 2.53.0