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 1747438E8AD; Fri, 7 Aug 2026 15:26:08 +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=1786116369; cv=none; b=jLvbRrjalHGbFawwiDNvaE35c89YrqhzsGN5suzzSyvnd9gkpKFltZvPjL9tma0MOFUnJs/cUyrckC0fXE69l3y7R1IQYRKb9WZhvOVg4V6pz0nTfLkv+GZLr6d9Nq3cEA2JNCsH84X1ssxbkyH+KUFkD/gJTmz9oVqi8CCfX48= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786116369; c=relaxed/simple; bh=1qAlJBD06nsmCb+BU/GlPyKOHNt5A+AAEDCSJu/9Q2M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EPdCk3mscuhzJ16iJ45BmzRV1B9NZrS8QqrXcci5dctX87YS+F1bcgl6XPygCk2XRWGfLB5sXIh1CE2FkK8rOGDBNMJDD+Z+spTd6NmYNt5qS0r2VVXhDQFRJ6BJmI5f4wBO9YdR5QNHBd/J4eYhvV8+tad0WRbhzz7FkzNHQ74= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=b2NefNFH; 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="b2NefNFH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69FE61F000E9; Fri, 7 Aug 2026 15:26:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786116368; bh=yIfXDNnBOvAshHy5ygA7wamOml59d5AJetJ4b/XeJus=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=b2NefNFHo6VipgBy7uo/SMxuu2TjGJ/SjoeFOht/vzYZ7EWXAYTa+jMN0PVqzTAx7 RmKyKwMJHihWo4BbbjYQ8DEo0ZNx8VQ+PIKhgoJJC7ywoq6zMGRHo80ZVkG7gq8kH5 0pxyMB6BHic5iNiR8oZokyfXIwiq/liUKyBezvkU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, HyeongJun An , Jiri Kosina Subject: [PATCH 6.6 205/261] HID: logitech-dj: Fix maxfield check in DJ short report validation Date: Fri, 7 Aug 2026 16:39:22 +0200 Message-ID: <20260807143419.787165961@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260807143415.358597922@linuxfoundation.org> References: <20260807143415.358597922@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 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: HyeongJun An commit 590cc4d782487632a52f37c2171bee1eeea29627 upstream. Commit b6a57912854e ("HID: logitech-dj: Prevent REPORT_ID_DJ_SHORT related user initiated OOB write") added validation for the DJ short output report, but the error path dereferences rep->field[0] even when rep->maxfield is zero. Commit 8b9a097eb2fc ("HID: logitech-dj: fix wrong detection of bad DJ_SHORT output report") made the check conditional on rep being present, but a crafted descriptor can still create report ID 0x20 with only padding output items. hid-core registers the report, ignores the padding field, and leaves rep->maxfield as zero. In that case the validation enters the rep->maxfield < 1 branch and then dereferences rep->field[0]->report_count while printing the error message, causing a NULL pointer dereference during probe. This is reproducible with uhid by emulating a Logitech receiver with a padding-only DJ short output report: BUG: KASAN: null-ptr-deref in logi_dj_probe+0xb1/0x754 [hid_logitech_dj] Read of size 4 at addr 0000000000000028 by task kworker/4:1/129 ... Call Trace: logi_dj_probe+0xb1/0x754 [hid_logitech_dj] hid_device_probe+0x329/0x3f0 [hid] really_probe+0x162/0x570 __device_attach+0x137/0x2c0 bus_probe_device+0x38/0xc0 device_add+0xa56/0xce0 hid_add_device+0x19c/0x280 [hid] uhid_device_add_worker+0x2c/0xb0 [uhid] Reject the zero-field report before printing the field report_count. Fixes: b6a57912854e ("HID: logitech-dj: Prevent REPORT_ID_DJ_SHORT related user initiated OOB write") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: HyeongJun An Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman --- drivers/hid/hid-logitech-dj.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/drivers/hid/hid-logitech-dj.c +++ b/drivers/hid/hid-logitech-dj.c @@ -1797,8 +1797,13 @@ static int logi_dj_probe(struct hid_devi output_report_enum = &hdev->report_enum[HID_OUTPUT_REPORT]; rep = output_report_enum->report_id_hash[REPORT_ID_DJ_SHORT]; - if (rep && (rep->maxfield < 1 || - rep->field[0]->report_count != DJREPORT_SHORT_LENGTH - 1)) { + if (rep && rep->maxfield < 1) { + hid_err(hdev, "Expected size of DJ short report is %d, but got 0", + DJREPORT_SHORT_LENGTH - 1); + return -EINVAL; + } + + if (rep && rep->field[0]->report_count != DJREPORT_SHORT_LENGTH - 1) { hid_err(hdev, "Expected size of DJ short report is %d, but got %d", DJREPORT_SHORT_LENGTH - 1, rep->field[0]->report_count); return -EINVAL;