From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729028AbgHaUiy (ORCPT ); Mon, 31 Aug 2020 16:38:54 -0400 From: Nicolin Chen Subject: [RESEND][PATCH 7/7] parisc: Avoid overflow at boundary_size Date: Mon, 31 Aug 2020 13:38:11 -0700 Message-Id: <20200831203811.8494-8-nicoleotsuka@gmail.com> In-Reply-To: <20200831203811.8494-1-nicoleotsuka@gmail.com> References: <20200831203811.8494-1-nicoleotsuka@gmail.com> Sender: linux-s390-owner@vger.kernel.org List-ID: To: mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, tony.luck@intel.com, fenghua.yu@intel.com, schnelle@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, James.Bottomley@HansenPartnership.com, deller@gmx.de Cc: sfr@canb.auug.org.au, hch@lst.de, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-parisc@vger.kernel.org The boundary_size might be as large as ULONG_MAX, which means that a device has no specific boundary limit. So either "+ 1" or passing it to ALIGN() would potentially overflow. According to kernel defines: #define ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask)) #define ALIGN(x, a) ALIGN_MASK(x, (typeof(x))(a) - 1) We can simplify the logic here: ALIGN(boundary + 1, 1 << shift) >> shift = ALIGN_MASK(b + 1, (1 << s) - 1) >> s = {[b + 1 + (1 << s) - 1] & ~[(1 << s) - 1]} >> s = [b + 1 + (1 << s) - 1] >> s = [b + (1 << s)] >> s = (b >> s) + 1 So fixing a potential overflow with the safer shortcut. Signed-off-by: Nicolin Chen Cc: Christoph Hellwig --- drivers/parisc/ccio-dma.c | 4 ++-- drivers/parisc/sba_iommu.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/parisc/ccio-dma.c b/drivers/parisc/ccio-dma.c index a5507f75b524..c667d6aba764 100644 --- a/drivers/parisc/ccio-dma.c +++ b/drivers/parisc/ccio-dma.c @@ -356,8 +356,8 @@ ccio_alloc_range(struct ioc *ioc, struct device *dev, size_t size) ** ggg sacrifices another 710 to the computer gods. */ - boundary_size = ALIGN((unsigned long long)dma_get_seg_boundary(dev) + 1, - 1ULL << IOVP_SHIFT) >> IOVP_SHIFT; + /* Overflow-free shortcut for: ALIGN(b + 1, 1 << s) >> s */ + boundary_size = (dma_get_seg_boundary(dev) >> IOVP_SHIFT) + 1; if (pages_needed <= 8) { /* diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c index d4314fba0269..96bc2c617cbd 100644 --- a/drivers/parisc/sba_iommu.c +++ b/drivers/parisc/sba_iommu.c @@ -342,8 +342,8 @@ sba_search_bitmap(struct ioc *ioc, struct device *dev, unsigned long shift; int ret; - boundary_size = ALIGN((unsigned long long)dma_get_seg_boundary(dev) + 1, - 1ULL << IOVP_SHIFT) >> IOVP_SHIFT; + /* Overflow-free shortcut for: ALIGN(b + 1, 1 << s) >> s */ + boundary_size = (dma_get_seg_boundary(dev) >> IOVP_SHIFT) + 1; #if defined(ZX1_SUPPORT) BUG_ON(ioc->ibase & ~IOVP_MASK); -- 2.17.1