From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7507C433E7 for ; Sat, 29 Aug 2020 11:29:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB2ED21527 for ; Sat, 29 Aug 2020 11:29:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598700592; bh=B9VCR1gc3mVExEe2V499pC1prwSxp/+jhKu43FvTLNU=; h=From:To:Cc:Subject:Date:List-ID:From; b=yFIoDwDnaJKDmCyRDSALb13jkeydo15zENaTEnYR321kC7wn0cZARQQPZa+NcC+qy bJx/+AeAbgcXB/nRDgncx8SsVbVGk/6ZNe22gRXRYfcvym58LI0ycS+rPVeC3hqh7n PuktoVOGnfEbmH9hGVWN3vSqKIL56txH6fU0+tYQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727913AbgH2L3v (ORCPT ); Sat, 29 Aug 2020 07:29:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:46396 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727999AbgH2L2G (ORCPT ); Sat, 29 Aug 2020 07:28:06 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D427F214DB; Sat, 29 Aug 2020 11:26:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598700369; bh=B9VCR1gc3mVExEe2V499pC1prwSxp/+jhKu43FvTLNU=; h=From:To:Cc:Subject:Date:From; b=zYwTfmnLzGYjYC7cBwL7UWSG8ImGKC3qfcDFucsRDuTTUP+MyQbSwuPojkS94jtBk mQsz9/czKDf45ZLMs/uyQ42zTe3k7muKVy41rHIhwzRi3k+fA6irRUjjL6fJKHwhLH v2NToLsTGTK2FN1AB+sRkSDYJA/BnetkQhQIJRPc= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kByzm-007dRY-Ra; Sat, 29 Aug 2020 12:26:07 +0100 From: Marc Zyngier To: Jiri Kosina , Benjamin Tissoires Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@android.com Subject: [PATCH] HID: core: Correctly handle ReportSize being zero Date: Sat, 29 Aug 2020 12:26:01 +0100 Message-Id: <20200829112601.1060527-1-maz@kernel.org> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: jikos@kernel.org, benjamin.tissoires@redhat.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It appears that a ReportSize value of zero is legal, even if a bit non-sensical. Most of the HID code seems to handle that gracefully, except when computing the total size in bytes. When fed as input to memset, this leads to some funky outcomes. Detect the corner case and correctly compute the size. Cc: stable@vger.kernel.org Signed-off-by: Marc Zyngier --- drivers/hid/hid-core.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 359616e3efbb..d2ecc9c45255 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1597,6 +1597,17 @@ static void hid_output_field(const struct hid_device *hid, } } +/* + * Compute the size of a report. + */ +static size_t hid_compute_report_size(struct hid_report *report) +{ + if (report->size) + return ((report->size - 1) >> 3) + 1; + + return 0; +} + /* * Create a report. 'data' has to be allocated using * hid_alloc_report_buf() so that it has proper size. @@ -1609,7 +1620,7 @@ void hid_output_report(struct hid_report *report, __u8 *data) if (report->id > 0) *data++ = report->id; - memset(data, 0, ((report->size - 1) >> 3) + 1); + memset(data, 0, hid_compute_report_size(report)); for (n = 0; n < report->maxfield; n++) hid_output_field(report->device, report->field[n], data); } @@ -1739,7 +1750,7 @@ int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size, csize--; } - rsize = ((report->size - 1) >> 3) + 1; + rsize = hid_compute_report_size(report); if (report_enum->numbered && rsize >= HID_MAX_BUFFER_SIZE) rsize = HID_MAX_BUFFER_SIZE - 1; -- 2.27.0