From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.82.175 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793731524; b=cZDuR/C2WSmKCAIWRqENzryEZMSqeQmPQwGd2s4nWwnXpQ4Q0sW3fuNLVrScGNDU1LEh +Qev2J1CsAZMDNL9O3L86ZKMg2wwHxPV4Su3otrSpHawv/1uGrKZWrHzYHrWHFIjFUe/i s+k9MOtKAnls9o4RZpAzHwhbpbsE/nlJNja/L65pGYriaTfd+3Qw8lCk+M+IZb9NJO23F yVAdKiQOvzrYPvmmTsB0jPWxMEjb/Akb8xwdGgfsuRPD7QN2kxWG2y+BTMcJq6q63lkor acpA5/sAemj8VaDXwhYWMK4eWTeyuTBmWJJZQ30f/tBaONJjWP2S+eZ7YdO9yCuW4iQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793731524; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; bh=dxl6974/XeNGL3VGfuMejNoLR+R+5VwHaUl0w+woIxw=; b=QlYyMhuRqR5hdJGTeRI1nUOV+/kXX+rzc4QlWDrpig1adxPk222rcn0N3B/306ykajwD Tt9RwBrTHT2BncM131fnxFdSL5LPu/93uprokF+yScpywrbDSuQ5yow5OBPJooGK1kYLQ K/Z9EEzwaBCu9O3/hZuNF/SHEe+QLOHPX2bAteKiePYDcYu5MWT/p00Rvo5+jMlnRwLJF iGQ3Lm94nBy8PidmQhfQAGLRJxhcbHb7QwJiN/y02MAAqSytJoRIthG1+MkWrNEbmaY8Y NXuDO0ugLKdaXhA5WafLQYsPiLvlFkwRlQT20600r1Pfv2E1KDrkzlOngketuCDsusQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b="bRn/Owv1"; arc=none smtp.remote-ip=74.125.82.175 Received: from mail-dy1-f175.google.com (mail-dy1-f175.google.com [74.125.82.175]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 169EF606A326 for ; Tue, 3 Nov 2026 18:45:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 169EF606A326 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=bRn/Owv1 Received: by mail-dy1-f175.google.com with SMTP id 5a478bee46e88-36a18fc7a38so8649913eec.1 for ; Tue, 03 Nov 2026 10:45:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793731523; x=1794336323; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=dxl6974/XeNGL3VGfuMejNoLR+R+5VwHaUl0w+woIxw=; b=bRn/Owv1Hbfs4AmSN8ZJ7uUv/i0z0jsI2n/FSJWVnU6sdNs5Vsb6Xm0EVSeeyfd25e s08GRHSnBiw1wt2ZJ57iKnFkzIRWVkEfnnoHjWhJR6uaMXyzdi2V1uY1dCOJnvcLcAGa tOl46D5H4NCfA8pH4ty8mpstLEBI841odDGE8iZL288BlhkJoNYgWzNsmV3/wZQvJ+Wd b1IW+EwkaujwJlpUkvjFTkIXOHtGxTisL8ZYCyaQVlXAw4Nhu+h4ZNRpfaPBcmrbx2YY dlot7YrLO0aHSIq4qsDCn2RGmFQI/dsYji3caC76+BjaLIBiVvV1Oes6fIIA41IYUj8V x01w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793731523; x=1794336323; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=dxl6974/XeNGL3VGfuMejNoLR+R+5VwHaUl0w+woIxw=; b=AKFDiHy69XLnYCRVD9NjHwfCS8i5lWDRPcTbIkO4uWjO7IwjN6ly9/Z9Ill/foMHaw NyR68hfFKEH2h2ciC9jw6qaXGNZHJ0E9VWpjLQTpp6V8sr2ImRFemUYyBfKkGAVa4KrL EIwLc+16/98+9g6mrvPEb9J8Z/mVqowH1gZpbgzk4imsWcLE2UITey2EjDeLQ5XFmJ1c ICzgauX6WwfzYYMk0ZfVhLBw+9p8hcjw5PMfRQZyyEMDa94ljBq1hRw0hId4zfrYzdgv 89Jvg/+vtTTifHCMx7j/8JDVO6x7i+C6JYrCrOn9VUAk8561JwR9qMKmu92SuHP/3TiA 1SyQ== X-Forwarded-Encrypted: i=1; AKwUvByULfFufUvU9A7j49fiRYWm5W87zPkU/a62kosh5SPJObAf0gFwgCtiaQFz/3odpGWAi0bvs7aNflWHp/Q=@vger.kernel.org X-Gm-Message-State: APuU4Z8L+7QwEfN0f2qTz80U1B6S5vfo8wGYJ6eYbLnFZs104bExZ9Xb 3MIW9DZeihatxa439qjX1/nf8Qj2biNtvEn7MXCyMz4+/GZ7JTr8/cYE X-Gm-Gg: AYBFou292Ma742e4x1hNEoB2kkp/j9n7rX8LuqSJ/s1z23vnQoRHClmTe2kVavPJOb+ C1Y/gBoJQgNjvf7satVumoy0V4jg/kiL813nWBuP61NYZZsICKdlhJFu0r8ymKCI6o5SNc9FKXy QsUFwRQ+1zhEK4aPHOT9MoZc66jEYFU45vccfsGD8OMGyFn8Jm1OSyTBQ3QUXY+pKdHcCSGe2+d FLckAI2TGZSLgZ2WKx+vSg7pGuBW62QjfMe833Gj5+qD5c6oCjExiyCH24Kb61Fl2udU8Kgqa6Z ZomLc8b4XSr3s/9vPwUuwYsFTsPM9x+1Rc3iMVKOAXTuw9ZrOsoyV6akxC8xRQHGxKH2BQM3sWO Gq3+gpJWC5TE+bLhBQKpyfozRN1u584rgt4dJ8a81f1GnFwZh/joC9M7bQcAGO2lyKmhuXAKanR lOuOstlJECvycA//mP2qLGPWuGkl38bSI4+qzOPMHZX6BKd8nqfGDfFji3NCD8/qs1EW7abpu2L qUC042jbUrVw3kCrmvVTB/UuRc/d3IaFVJiJV6+6OonQfoqDfTx6mJCLA9NSeiV5l3RARE4/jvk YZ4N3tF0HwsQJ7D5lEaNwx+s2xrnO8hHi1+QepXVcXw6KPRdc05Qs8vThOe+CB/w5y+Jre5jA4z TOlJjuouZrJ+MyA== X-Received: by 2002:a05:7301:648a:b0:369:d793:328d with SMTP id 5a478bee46e88-36c9dd475camr1585502eec.31.1793731523122; Tue, 03 Nov 2026 10:45:23 -0800 (PST) Received: from google.com ([2a00:79e0:2ebe:8:88b4:22ec:d621:c1b]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36ca3788bffsm102648eec.1.2026.11.03.10.45.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Nov 2026 10:45:22 -0800 (PST) Date: Tue, 3 Nov 2026 10:45:18 -0800 From: Dmitry Torokhov To: Guanglei Zhu Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, liuc63@xiaopeng.com, stable@vger.kernel.org Subject: Re: [PATCH] Input: joydev - avoid an undefined shift in the legacy 0x read Message-ID: References: <20261103084135.426629-1-zhugl3@xiaopeng.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261103084135.426629-1-zhugl3@xiaopeng.com> Hi Guanglei, On Tue, Nov 03, 2026 at 04:41:28PM +0800, Guanglei Zhu wrote: > The legacy 0.x read path shifts the axis values by the calibration > constants that JS_SET_CAL installs: > > data.x = (joydev->abs[0] / 256 + 128) >> joydev->glue.JS_CORR.x; > data.y = (joydev->abs[1] / 256 + 128) >> joydev->glue.JS_CORR.y; > > JS_CORR is copied straight from userspace as three s32 values and > never validated, so the shift count can be negative or wider than > the type, which is undefined behavior: the shift compiles to > whatever the architecture does with an out-of-range count, and the > compiler is free to assume it cannot happen. > > Clamp the shift count to the width of the shifted value. > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Cc: stable@vger.kernel.org Why do all these need to be in stable? > Signed-off-by: Guanglei Zhu > --- > drivers/input/joydev.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/input/joydev.c b/drivers/input/joydev.c > index 32459fd8a7c1..4740099599bf 100644 > --- a/drivers/input/joydev.c > +++ b/drivers/input/joydev.c > @@ -353,8 +353,8 @@ static ssize_t joydev_0x_read(struct joydev_client *client, > for (data.buttons = i = 0; i < 32 && i < joydev->nkey; i++) > data.buttons |= > test_bit(joydev->keypam[i], input->key) ? (1 << i) : 0; > - data.x = (joydev->abs[0] / 256 + 128) >> joydev->glue.JS_CORR.x; > - data.y = (joydev->abs[1] / 256 + 128) >> joydev->glue.JS_CORR.y; > + data.x = (joydev->abs[0] / 256 + 128) >> clamp(joydev->glue.JS_CORR.x, 0, 31); > + data.y = (joydev->abs[1] / 256 + 128) >> clamp(joydev->glue.JS_CORR.y, 0, 31); > > /* > * Reset reader's event queue Thanks. -- Dmitry