Since commit 69031f500865 ("swiotlb: Set dev->dma_io_tlb_mem to the
swiotlb pool used"), 'struct device' may hold a copy of the global
'io_default_tlb_mem' pointer if the device is using swiotlb for DMA. A
subsequent call to swiotlb_exit() will therefore leave dangling pointers
behind in these device structures, resulting in KASAN splats such as:| BUG: KASAN: use-after-free in __iommu_dma_unmap_swiotlb+0x64/0xb0 | Read of size 8 at addr ffff8881d7830000 by task swapper/0/0 | | CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.12.0-rc3-debug #1 | Hardware name: HP HP Desktop M01-F1xxx/87D6, BIOS F.12 12/17/2020 | Call Trace: | <IRQ> | dump_stack+0x9c/0xcf | print_address_description.constprop.0+0x18/0x130 | kasan_report.cold+0x7f/0x111 | __iommu_dma_unmap_swiotlb+0x64/0xb0 | nvme_pci_complete_rq+0x73/0x130 | blk_complete_reqs+0x6f/0x80 | __do_softirq+0xfc/0x3be Point 'io_default_tlb_mem' at a static structure, so that the per-device pointers remain valid after swiotlb_exit() has been invoked. The 'slots' array is still allocated dynamically and referenced via a pointer rather than a flexible array member. Cc: Claire Chang <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Robin Murphy <[email protected]> Cc: Konrad Rzeszutek Wilk <[email protected]> Fixes: 69031f500865 ("swiotlb: Set dev->dma_io_tlb_mem to the swiotlb pool used") Reported-by: Nathan Chancellor <[email protected]> Tested-by: Nathan Chancellor <[email protected]> Signed-off-by: Will Deacon <[email protected]> --- include/linux/swiotlb.h | 2 +- kernel/dma/swiotlb.c | 34 +++++++++++++++++++++------------- 2 files changed, 22 insertions(+), 14 deletions(-) diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h index 39284ff2a6cd..d3b617c19045 100644 --- a/include/linux/swiotlb.h +++ b/include/linux/swiotlb.h @@ -103,7 +103,7 @@ struct io_tlb_mem { phys_addr_t orig_addr; size_t alloc_size; unsigned int list; - } slots[]; + } *slots; }; extern struct io_tlb_mem *io_tlb_default_mem; diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index f1a9ae7fad8f..992d73cdc944 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -71,6 +71,7 @@ enum swiotlb_force swiotlb_force; struct io_tlb_mem *io_tlb_default_mem; +static struct io_tlb_mem _io_tlb_default_mem; /* * Max segment that we can provide which (if pages are contingous) will @@ -201,7 +202,7 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start, int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose) { - struct io_tlb_mem *mem; + struct io_tlb_mem *mem = &_io_tlb_default_mem; size_t alloc_size; if (swiotlb_force == SWIOTLB_NO_FORCE) @@ -211,9 +212,9 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose) if (WARN_ON_ONCE(io_tlb_default_mem)) return -ENOMEM; - alloc_size = PAGE_ALIGN(struct_size(mem, slots, nslabs)); - mem = memblock_alloc(alloc_size, PAGE_SIZE); - if (!mem) + alloc_size = PAGE_ALIGN(array_size(sizeof(*mem->slots), nslabs)); + mem->slots = memblock_alloc(alloc_size, PAGE_SIZE); + if (!mem->slots) panic("%s: Failed to allocate %zu bytes align=0x%lx\n", __func__, alloc_size, PAGE_SIZE); @@ -304,7 +305,7 @@ swiotlb_late_init_with_default_size(size_t default_size) int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs) { - struct io_tlb_mem *mem; + struct io_tlb_mem *mem = &_io_tlb_default_mem; unsigned long bytes = nslabs << IO_TLB_SHIFT; if (swiotlb_force == SWIOTLB_NO_FORCE) @@ -314,12 +315,11 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs) if (WARN_ON_ONCE(io_tlb_default_mem)) return -ENOMEM; - mem = (void *)__get_free_pages(GFP_KERNEL, - get_order(struct_size(mem, slots, nslabs))); - if (!mem) + mem->slots = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, + get_order(array_size(sizeof(*mem->slots), nslabs))); + if (!mem->slots) return -ENOMEM; - memset(mem, 0, sizeof(*mem)); set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT); swiotlb_init_io_tlb_mem(mem, virt_to_phys(tlb), nslabs, true); @@ -337,12 +337,13 @@ void __init swiotlb_exit(void) if (!mem) return; - size = struct_size(mem, slots, mem->nslabs); + size = array_size(sizeof(*mem->slots), mem->nslabs); if (mem->late_alloc) - free_pages((unsigned long)mem, get_order(size)); + free_pages((unsigned long)mem->slots, get_order(size)); else - memblock_free_late(__pa(mem), PAGE_ALIGN(size)); + memblock_free_late(__pa(mem->slots), PAGE_ALIGN(size)); io_tlb_default_mem = NULL; + memset(mem, 0, sizeof(*mem)); } /* @@ -783,10 +784,17 @@ static int rmem_swiotlb_device_init(struct reserved_mem *rmem, * to it. */ if (!mem) { - mem = kzalloc(struct_size(mem, slots, nslabs), GFP_KERNEL); + mem = kzalloc(sizeof(*mem), GFP_KERNEL); if (!mem) return -ENOMEM; + mem->slots = kzalloc(array_size(sizeof(*mem->slots), nslabs), + GFP_KERNEL); + if (!mem->slots) { + kfree(mem); + return -ENOMEM; + } + set_memory_decrypted((unsigned long)phys_to_virt(rmem->base), rmem->size >> PAGE_SHIFT); swiotlb_init_io_tlb_mem(mem, rmem->base, nslabs, false); -- 2.32.0.402.g57bb445576-goog _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
