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 1080132B110; Thu, 20 Aug 2026 15:05:22 +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=1787238323; cv=none; b=UqwGT5cdKEhh9J0xqZ4Skx2Rs/eQeffdrqRLPxuJKLnuuaZqA8LDXlcPyvpVixqsN5QeGyt7Jw3so+34JoxW7UCoOGyxe6xOAPZF1BAF26VhKCC++sGkrH4CsA3F+DXhEOto/cKKKM8wq+YPiGozz36znP1sFqafzmc2db5T2HA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787238323; c=relaxed/simple; bh=wJ1yRTxc/UyPqoaS66RR+6TVPL5S4ry3zPXNBA7Drig=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lXiQF7ml7H6B2rOvTRP0RBOwTUY69EgNvCbemlQRHKQtNnD3Rxe6IvTWCUdof5pLxvbz8hsCPofX8lNKKUkmXgT5oN8XWEZ1YOxr+hQvOdRUSfjHd0aZBg/0x5hn8upyrK7r7geP6l+XsgHMFxZROONSYOCTXMdXWa8iloS7dzo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EuUywNfP; 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="EuUywNfP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 656AA1F000E9; Thu, 20 Aug 2026 15:05:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787238321; bh=m3caYpDvKoKryGd4IPFSDsdFQMalMUluSouRtGHt74c=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EuUywNfPx7IfI0Tax8p2+FXRwPEQjxlphuOo4o6MDLdXcMHCZAF8Cd0zBc9Rb+BMU kQtjo/KYsFKjnLZwI/dIZ4VyzasLPqmx7XvcY/uKdzryC7fszRqcJuKjkFFHsdSYgZ zFIG+gI0JiATc3jxNFxAi7uI+BnX+0SM/bCjsTGM= 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 7.1 100/228] s390/vfio_ccw: Fix out of bounds check on CCW array Date: Thu, 20 Aug 2026 16:54:02 +0200 Message-ID: <20260820145247.690635316@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260820145244.450574346@linuxfoundation.org> References: <20260820145244.450574346@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 7.1-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)