Messages in this thread Patch in this message | | | From | Walter Wu <> | Subject | [PATCH] arm64: kasan: fix phys_to_virt() false positive on tag-based kasan | Date | Mon, 19 Aug 2019 19:44:20 +0800 |
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__arm_v7s_unmap() call iopte_deref() to translate pyh_to_virt address, but it will modify pointer tag into 0xff, so there is a false positive.
When enable tag-based kasan, phys_to_virt() function need to rewrite its original pointer tag in order to avoid kasan report an incorrect memory corruption.
BUG: KASAN: double-free or invalid-free in __arm_v7s_unmap+0x720/0xda4 Pointer tag: [ff], memory tag: [c1]
Call trace: dump_backtrace+0x0/0x1d4 show_stack+0x14/0x1c dump_stack+0xe8/0x140 print_address_description+0x80/0x2f0 kasan_report_invalid_free+0x58/0x74 __kasan_slab_free+0x1e4/0x220 kasan_slab_free+0xc/0x18 kmem_cache_free+0xfc/0x884 __arm_v7s_unmap+0x720/0xda4 __arm_v7s_map+0xc8/0x774 arm_v7s_map+0x80/0x158 mtk_iommu_map+0xb4/0xe0 iommu_map+0x154/0x450 iommu_map_sg+0xe4/0x150 iommu_dma_map_sg+0x214/0x4ec __iommu_map_sg_attrs+0xf0/0x110 ion_map_dma_buf+0xe8/0x114 dma_buf_map_attachment+0x4c/0x80 disp_sync_prepare_buf+0x378/0x820 _ioctl_prepare_buffer+0x130/0x870 mtk_disp_mgr_ioctl+0x5c4/0xab0 do_vfs_ioctl+0x8e0/0x15a4 __arm64_sys_ioctl+0x8c/0xb4 el0_svc_common+0xe4/0x1e0 el0_svc_handler+0x30/0x3c el0_svc+0x8/0xc
Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com> --- arch/arm64/include/asm/kasan.h | 1 - arch/arm64/include/asm/memory.h | 10 ++++++++++ 2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/kasan.h b/arch/arm64/include/asm/kasan.h index b52aacd2c526..59894cafad60 100644 --- a/arch/arm64/include/asm/kasan.h +++ b/arch/arm64/include/asm/kasan.h @@ -5,7 +5,6 @@ #ifndef __ASSEMBLY__ #include <linux/linkage.h> -#include <asm/memory.h> #include <asm/pgtable-types.h> #define arch_kasan_set_tag(addr, tag) __tag_set(addr, tag) diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 8ffcf5a512bb..75af5ba9ff22 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -171,6 +171,7 @@ #include <linux/bitops.h> #include <linux/mmdebug.h> +#include <asm/kasan.h> extern s64 memstart_addr; /* PHYS_OFFSET - the physical address of the start of memory. */ @@ -282,7 +283,16 @@ static inline phys_addr_t virt_to_phys(const volatile void *x) #define phys_to_virt phys_to_virt static inline void *phys_to_virt(phys_addr_t x) { +#ifdef CONFIG_KASAN_SW_TAGS + unsigned long addr = __phys_to_virt(x); + u8 *tag = (void *)(addr >> KASAN_SHADOW_SCALE_SHIFT) + + KASAN_SHADOW_OFFSET; + + addr = __tag_set(addr, *tag); + return (void *)addr; +#else return (void *)(__phys_to_virt(x)); +#endif } /* -- 2.18.0
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