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 5924637E5E5; Thu, 20 Aug 2026 15:17:03 +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=1787239024; cv=none; b=cnD+88JNFnkteYIrMoGGka/RpqALEE+Jj8koDySt2piY/UHTDplyWPdbC3d/Tl/8YkNPqmu1spEL74ipn8VCN+TaskFxHtyoTS4SmLySsGJYuWVo0S1cwVZnzPtudrjmqIXkRKMDtG7Pm6ORPl5D310AVIuuW8RVBH1S/oUAMkg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787239024; c=relaxed/simple; bh=jlfimkIGRwc7yQk9GD2fp+LVaeKTAUPaIhi8KcY0uvo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=A7/HKL68gZzdHeyIINsllwGlpp8kQFef9gFr9wZRvBiH5sK7Wn30mpRkmIFinqHt6+Y7rsIgI8hUVMJqV+uesjax18oQ70u9HPKGj7EdPTcai2QR9D6H7xVIGsDUCcDGFfj3ChkrbyYZ+KYWS/ayPW//mIQHfpYFvtDWlav1HbU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=n1NGFbaj; 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="n1NGFbaj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD35E1F000E9; Thu, 20 Aug 2026 15:17:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787239023; bh=ER6e0NZcLWxcrGZTqZ44toNUQYhUvG/xeZqzlgXqnoc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=n1NGFbajwFynuQW+NigwBS45Fw7TceyJ7i/cQQnXOZMldLkIuZclfRqWINybDxKoV VxRpzSQaiqDmlYg8MgIs5KyNAH7Subzq5gGVOBMyn44bVaD327w+oSayYAhmoRYfBN 0fWLXemcg3KbDRp8t4sCrV4CLmjO3VA/F5aRIrjE= 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 6.18 084/217] s390/vfio_ccw: Fix out of bounds check on CCW array Date: Thu, 20 Aug 2026 16:54:12 +0200 Message-ID: <20260820145240.158547365@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145237.531699751@linuxfoundation.org> References: <20260820145237.531699751@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-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)