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 7CFE13F88B9; Mon, 17 Aug 2026 14:17:10 +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=1786976231; cv=none; b=Upp4zfWvknblQE3Y/Cz/Rve+4djg9HAjpILPnmilt9ilZSqVreOLzQd6U9ltE+nzHW+XS1u8LGcy9KimIO1p4EpCXk8MQCWzlQv7Kq8iQd7W0KeX466kvu/3vraC9YldvspIUGaZumjTyAs3rlf9OVpdncpMwHK9U5SVEOMYG9I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786976231; c=relaxed/simple; bh=zDFfR5mKNac+pJ0Zat7bRua6Qih9Yk62F85Awvp7M+s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=W0laUmdLg6DKfqPsNjNlszC9evMRqx+V8tK5x8p4MyeYtPRArwgLJ581+lkJwmjrDMvBxvXYE/I7msgejv8fjuakTiES6fFvr79xjIvaGJ0gDBxBjbyIdnBJvD3Ypl2m1x/Mty8iO+EUr3itmWfsxo41ncrU2AfvN+34KarWRLg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xwPAYh7y; 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="xwPAYh7y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6CC01F000E9; Mon, 17 Aug 2026 14:17:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786976230; bh=TSYywbBuwgL8nxktvyehmFKmknhCzA0vSJnEQO7NyUM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=xwPAYh7yWkzdVhAg74yct5PHuehd6HNGnjY5YpaFzXYHm4IDJcOkpz3gnNQmfh6BE v+euUCL7Ealg8EFe23fVYoFSBmUAdC0jBlERO2rKJ8cS8QFy03FeEj3VzKEjwySlOJ p7TFG/8DuzyVqcGVnd34ZXJcOmAVmOq5JSsO8s/Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, HyeongJun An , Jiri Kosina Subject: [PATCH 5.10 302/389] HID: logitech-dj: Fix maxfield check in DJ short report validation Date: Mon, 17 Aug 2026 15:32:21 +0200 Message-ID: <20260817132550.830003278@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132538.796021292@linuxfoundation.org> References: <20260817132538.796021292@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: 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 @@ -1715,8 +1715,13 @@ 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;