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authorJean-Philippe Brucker <jean-philippe.brucker@arm.com>2018-06-19 15:52:24 +0300
committerWill Deacon <will.deacon@arm.com>2018-07-26 13:34:58 +0300
commit29859aeb8a6ea17ba207933a81b6b77b4d4df81a (patch)
treea2a556c2138d72570abb71760f9385464943e201 /drivers/iommu
parentfac83d29d95471ad6a104f8c0d21669a3d59097b (diff)
downloadlinux-29859aeb8a6ea17ba207933a81b6b77b4d4df81a.tar.xz
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>
Diffstat (limited to 'drivers/iommu')
-rw-r--r--drivers/iommu/io-pgtable-arm-v7s.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c
index 50e3a9fcf43e..b5948ba6b3b3 100644
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c
@@ -192,6 +192,7 @@ static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
{
struct io_pgtable_cfg *cfg = &data->iop.cfg;
struct device *dev = cfg->iommu_dev;
+ phys_addr_t phys;
dma_addr_t dma;
size_t size = ARM_V7S_TABLE_SIZE(lvl);
void *table = NULL;
@@ -200,6 +201,10 @@ static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
table = (void *)__get_dma_pages(__GFP_ZERO, get_order(size));
else if (lvl == 2)
table = kmem_cache_zalloc(data->l2_tables, gfp | GFP_DMA);
+ phys = virt_to_phys(table);
+ if (phys != (arm_v7s_iopte)phys)
+ /* Doesn't fit in PTE */
+ goto out_free;
if (table && !(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA)) {
dma = dma_map_single(dev, table, size, DMA_TO_DEVICE);
if (dma_mapping_error(dev, dma))
@@ -209,7 +214,7 @@ static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
* address directly, so if the DMA layer suggests otherwise by
* translating or truncating them, that bodes very badly...
*/
- if (dma != virt_to_phys(table))
+ if (dma != phys)
goto out_unmap;
}
kmemleak_ignore(table);