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 A3BAE38331C; Thu, 20 Aug 2026 15:25:10 +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=1787239511; cv=none; b=A8RzKSuU04n6oZ6m7soEkD089tC9ogW6Oj1ECEUREDokni1jlcREHSbgZA6eFf1eDEXcskw34VbH4uoJi7OolJ1c5ow5+mLMEzzmJFje5eWKJbt76PiDrvyjDGrJ2Y9C6UON6vgVLN4rYjneWnNaYfDXT6ZStkjBewOzK1PMTf0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787239511; c=relaxed/simple; bh=lLc4EMTLijnzo2WYMbvxIWGl46szAStS50aWGtkc/4c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PsDuHVPwaP17q9Yf98HucjNXcaOAqZvtEa/pF55fsTZfa/PDOjJcKoZK2f0t3/O+SPsrNRn/xiclt6ONs5PzEWY92X+pAwNtbo6gzcSqV9DI90Z+q9b6JAsy6RTUdPnm+RMBv75BVO/yW/bcBSTt2EPPuKTEcTbvOJYmFmk6TtY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=GKlwkTji; 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="GKlwkTji" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 072191F000E9; Thu, 20 Aug 2026 15:25:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787239510; bh=jtlRfIZQU/d4P9bylwhy+NQCaPdZ4Slb8fVsKqaNvps=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GKlwkTjiW5170cxleDEeU9SWqci+jyiCsO5P/2Az5GhrC/+kUgnnoTNi+FWxH9P1V bqQ0Ugp1XCR0Zaxm4b74S9e7crvRSSQZWvaOn1fO2pU32EblctanbLeaRIrenvTMZd 23msbDK/5QCXBDG/upFm3/H0/zvf+8WHtfoLXs1U= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Matthew Rosato , Eric Farman , Christian Borntraeger Subject: [PATCH 6.12 075/220] s390/vfio_ccw: Fix out of bounds check on CCW array Date: Thu, 20 Aug 2026 16:54:25 +0200 Message-ID: <20260820145225.745349971@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145223.480031205@linuxfoundation.org> References: <20260820145223.480031205@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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Farman commit a005b7f1a491ffda61bff0fd0f6548f8986fb977 upstream. The routine ccwchain_calc_length() counts the number of channel command words (CCWs) that are chained together in a single channel program, and rejects anything larger than CCWCHAIN_LEN_MAX (256) CCWs. The loop itself is "do..while (count < 257)", and while the logic in is_cpa_within_range() correctly adjusts between the 0-index array of CCWs and the count of CCWs starting at 1, this means it would look at a possible 257th CCW before ending the loop and (correctly) returning an error. Fix this by restructuring the loop to break as soon as 256 CCWs (thus indexes 0-255) are examined, without looking at memory outside the range. Fixes: 0a19e61e6d4c ("vfio: ccw: introduce channel program interfaces") Cc: stable@vger.kernel.org Reviewed-by: Matthew Rosato Signed-off-by: Eric Farman Signed-off-by: Christian Borntraeger Signed-off-by: Greg Kroah-Hartman --- drivers/s390/cio/vfio_ccw_cp.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) --- a/drivers/s390/cio/vfio_ccw_cp.c +++ b/drivers/s390/cio/vfio_ccw_cp.c @@ -377,11 +377,9 @@ static void ccwchain_cda_free(struct ccw static int ccwchain_calc_length(u64 iova, struct channel_program *cp) { struct ccw1 *ccw = cp->guest_cp; - int cnt = 0; - - do { - cnt++; + int cnt; + for (cnt = 1; cnt <= CCWCHAIN_LEN_MAX; cnt++, ccw++) { /* * We want to keep counting if the current CCW has the * command-chaining flag enabled, or if it is a TIC CCW @@ -391,15 +389,10 @@ static int ccwchain_calc_length(u64 iova * after the TIC, depending on the results of its operation. */ if (!ccw_is_chain(ccw) && !is_tic_within_range(ccw, iova, cnt)) - break; - - ccw++; - } while (cnt < CCWCHAIN_LEN_MAX + 1); - - if (cnt == CCWCHAIN_LEN_MAX + 1) - cnt = -EINVAL; + return cnt; + } - return cnt; + return -EINVAL; } static int tic_target_chain_exists(struct ccw1 *tic, struct channel_program *cp)