From f06da55596675383fbf2563fe2919b2a8f68901b Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 10 Jun 2021 12:41:26 -0700 Subject: [PATCH] swiotlb: manipulate orig_addr when tlb_addr has offset MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit in case of driver wants to sync part of ranges with offset, swiotlb_tbl_sync_single() copies from orig_addr base to tlb_addr with offset and ends up with data mismatch. It was removed from "swiotlb: don't modify orig_addr in swiotlb_tbl_sync_single", but said logic has to be added back in. [From Linus's email: That commit which the removed the offset calculation entirely, because the old (unsigned long)tlb_addr & (IO_TLB_SIZE - 1) was wrong, but instead of removing it, I think it should have just fixed it to be (tlb_addr - mem->start) & (IO_TLB_SIZE - 1); instead. That way the slot offset always matches the slot index calculation.] The use-case that drivers are hitting is as follow: 1. Get dma_addr_t from dma_map_single() dma_addr_t tlb_addr = dma_map_single(dev, vaddr, vsize, DMA_TO_DEVICE); |<---------------vsize------------->| +-----------------------------------+ | | original buffer +-----------------------------------+ vaddr swiotlb_align_offset |<----->|<---------------vsize------------->| +-------+-----------------------------------+ | | | swiotlb buffer +-------+-----------------------------------+ tlb_addr 2. Do something 3. Sync dma_addr_t through dma_sync_single_for_device(..) dma_sync_single_for_device(dev, tlb_addr + offset, size, DMA_TO_DEVICE); Error case. Copy data to original buffer but it is from base addr (instead of base addr + offset) in original buffer: swiotlb_align_offset |<----->|<- offset ->|<- size ->| +-------+-----------------------------------+ | | |##########| | swiotlb buffer +-------+-----------------------------------+ tlb_addr |<- size ->| +-----------------------------------+ |##########| | original buffer +-----------------------------------+ vaddr The fix is to copy the data to the original buffer and take into account the offset, like so: swiotlb_align_offset |<----->|<- offset ->|<- size ->| +-------+-----------------------------------+ | | |##########| | swiotlb buffer +-------+-----------------------------------+ tlb_addr |<- offset ->|<- size ->| +-----------------------------------+ | |##########| | original buffer +-----------------------------------+ vaddr [This patch text is from Bumyong's email; and his solution was very close to Linus's, so incorporating his text] Fixes: 16fc3cef33a0 ("swiotlb: don't modify orig_addr in swiotlb_tbl_sync_single") Signed-off-by: Bumyong Lee Signed-off-by: Chanho Park Reviewed-by: Christoph Hellwig Reported-by: Dominique MARTINET Reported-by: Horia Geantă Tested-by: Horia Geantă Signed-off-by: Linus Torvalds CC: stable@vger.kernel.org Signed-off-by: Konrad Rzeszutek Wilk --- kernel/dma/swiotlb.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 8ca7d50..dc438b5 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -342,6 +342,7 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size { struct io_tlb_mem *mem = io_tlb_default_mem; int index = (tlb_addr - mem->start) >> IO_TLB_SHIFT; + unsigned int offset = (tlb_addr - mem->start) & (IO_TLB_SIZE - 1); phys_addr_t orig_addr = mem->slots[index].orig_addr; size_t alloc_size = mem->slots[index].alloc_size; unsigned long pfn = PFN_DOWN(orig_addr); @@ -350,6 +351,14 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size if (orig_addr == INVALID_PHYS_ADDR) return; + if (offset > alloc_size) { + dev_WARN_ONCE(dev, 1, + "Buffer overflow detected. Offset: %lu. Mapping size: %zu.\n", + offset, size); + return; + } + alloc_size -= offset; + orig_addr += offset; if (size > alloc_size) { dev_WARN_ONCE(dev, 1, "Buffer overflow detected. Allocation size: %zu. Mapping size: %zu.\n", -- 1.8.3.1