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iommu/io-pgtable-arm-v7s: Abort allocation when table address overflows the PTE
When run on a 64-bit system in selftest, the v7s driver may obtain page table with physical addresses larger than 32-bit. Level-2 tables are 1KB and are are allocated with slab, which doesn't accept the GFP_DMA32 flag. Currently map() truncates the address written in the PTE, causing iova_to_phys() or unmap() to access invalid memory. Kasan reports it as a use-after-free. To avoid any nasty surprise, test if the physical address fits in a PTE before returning a new table. 32-bit systems, which are the main users of this page table format, shouldn't see any difference. Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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1 changed files with 6 additions and 1 deletions
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@ -192,6 +192,7 @@ static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
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{
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struct io_pgtable_cfg *cfg = &data->iop.cfg;
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struct device *dev = cfg->iommu_dev;
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phys_addr_t phys;
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dma_addr_t dma;
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size_t size = ARM_V7S_TABLE_SIZE(lvl);
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void *table = NULL;
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@ -200,6 +201,10 @@ static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
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table = (void *)__get_dma_pages(__GFP_ZERO, get_order(size));
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else if (lvl == 2)
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table = kmem_cache_zalloc(data->l2_tables, gfp | GFP_DMA);
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phys = virt_to_phys(table);
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if (phys != (arm_v7s_iopte)phys)
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/* Doesn't fit in PTE */
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goto out_free;
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if (table && !(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA)) {
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dma = dma_map_single(dev, table, size, DMA_TO_DEVICE);
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if (dma_mapping_error(dev, dma))
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@ -209,7 +214,7 @@ static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
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* address directly, so if the DMA layer suggests otherwise by
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* translating or truncating them, that bodes very badly...
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*/
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if (dma != virt_to_phys(table))
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if (dma != phys)
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goto out_unmap;
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}
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kmemleak_ignore(table);
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