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| author | Catalin Marinas <catalin.marinas@arm.com> | 2022-06-10 16:21:39 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2022-07-07 10:48:37 +0100 |
| commit | 70c248aca9e7efa85a6664d5ab56c17c326c958f (patch) | |
| tree | 1cee0c376af4662b3f7bf8982187e3492dff1b63 | |
| parent | ed0a6d1d973e9763989b44913ae1bd2a5d5d5777 (diff) | |
| download | linux-70c248aca9e7efa85a6664d5ab56c17c326c958f.tar.gz linux-70c248aca9e7efa85a6664d5ab56c17c326c958f.tar.bz2 linux-70c248aca9e7efa85a6664d5ab56c17c326c958f.zip | |
mm: kasan: Skip unpoisoning of user pages
Commit c275c5c6d50a ("kasan: disable freed user page poisoning with HW
tags") added __GFP_SKIP_KASAN_POISON to GFP_HIGHUSER_MOVABLE. A similar
argument can be made about unpoisoning, so also add
__GFP_SKIP_KASAN_UNPOISON to user pages. To ensure the user page is
still accessible via page_address() without a kasan fault, reset the
page->flags tag.
With the above changes, there is no need for the arm64
tag_clear_highpage() to reset the page->flags tag.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20220610152141.2148929-3-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | arch/arm64/mm/fault.c | 1 | ||||
| -rw-r--r-- | include/linux/gfp.h | 2 | ||||
| -rw-r--r-- | mm/page_alloc.c | 7 |
3 files changed, 6 insertions, 4 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index c5e11768e5c1..cdf3ffa0c223 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -927,6 +927,5 @@ struct page *alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma, void tag_clear_highpage(struct page *page) { mte_zero_clear_page_tags(page_address(page)); - page_kasan_tag_reset(page); set_bit(PG_mte_tagged, &page->flags); } diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 2d2ccae933c2..0ace7759acd2 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -348,7 +348,7 @@ struct vm_area_struct; #define GFP_DMA32 __GFP_DMA32 #define GFP_HIGHUSER (GFP_USER | __GFP_HIGHMEM) #define GFP_HIGHUSER_MOVABLE (GFP_HIGHUSER | __GFP_MOVABLE | \ - __GFP_SKIP_KASAN_POISON) + __GFP_SKIP_KASAN_POISON | __GFP_SKIP_KASAN_UNPOISON) #define GFP_TRANSHUGE_LIGHT ((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \ __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM) #define GFP_TRANSHUGE (GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index e008a3df0485..f6ed240870bc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2397,6 +2397,7 @@ inline void post_alloc_hook(struct page *page, unsigned int order, bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) && !should_skip_init(gfp_flags); bool init_tags = init && (gfp_flags & __GFP_ZEROTAGS); + int i; set_page_private(page, 0); set_page_refcounted(page); @@ -2422,8 +2423,6 @@ inline void post_alloc_hook(struct page *page, unsigned int order, * should be initialized as well). */ if (init_tags) { - int i; - /* Initialize both memory and tags. */ for (i = 0; i != 1 << order; ++i) tag_clear_highpage(page + i); @@ -2438,6 +2437,10 @@ inline void post_alloc_hook(struct page *page, unsigned int order, /* Note that memory is already initialized by KASAN. */ if (kasan_has_integrated_init()) init = false; + } else { + /* Ensure page_address() dereferencing does not fault. */ + for (i = 0; i != 1 << order; ++i) + page_kasan_tag_reset(page + i); } /* If memory is still not initialized, do it now. */ if (init) |