From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolin Chen Date: Thu, 20 Aug 2020 23:19:23 +0000 Subject: [RFT][PATCH 0/7] Avoid overflow at boundary_size Message-Id: <20200820231923.23678-1-nicoleotsuka@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 We are expending the default DMA segmentation boundary to its possible maximum value (ULONG_MAX) to indicate that a device doesn't specify a boundary limit. So all dma_get_seg_boundary callers should take a precaution with the return values since it would easily get overflowed. I scanned the entire kernel tree for all the existing callers and found that most of callers may get overflowed in two ways: either "+ 1" or passing it to ALIGN() that does "+ mask". 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 this series of patches fix the potential overflow with this overflow-free shortcut. As I don't think that I have these platforms, marking RFT. Thanks Nic Nicolin Chen (7): powerpc/iommu: Avoid overflow at boundary_size alpha: Avoid overflow at boundary_size ia64/sba_iommu: Avoid overflow at boundary_size s390/pci_dma: Avoid overflow at boundary_size sparc: Avoid overflow at boundary_size x86/amd_gart: Avoid overflow at boundary_size parisc: Avoid overflow at boundary_size arch/alpha/kernel/pci_iommu.c | 10 ++++------ arch/ia64/hp/common/sba_iommu.c | 4 ++-- arch/powerpc/kernel/iommu.c | 11 +++++------ arch/s390/pci/pci_dma.c | 4 ++-- arch/sparc/kernel/iommu-common.c | 9 +++------ arch/sparc/kernel/iommu.c | 4 ++-- arch/sparc/kernel/pci_sun4v.c | 4 ++-- arch/x86/kernel/amd_gart_64.c | 4 ++-- drivers/parisc/ccio-dma.c | 4 ++-- drivers/parisc/sba_iommu.c | 4 ++-- 10 files changed, 26 insertions(+), 32 deletions(-) -- 2.17.1