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authorAndrey Konovalov <andreyknvl@google.com>2022-03-25 04:11:32 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-25 05:06:48 +0300
commit23689e91fb22c15b84ac6c22ad9942039792f3af (patch)
tree43d39324d73f7b154524c966a9d49ec552faf6d4 /mm/kasan/shadow.c
parent9353ffa6e9e90d2b6348209cf2b95a8ffee18711 (diff)
downloadlinux-23689e91fb22c15b84ac6c22ad9942039792f3af.tar.xz
kasan, vmalloc: add vmalloc tagging for HW_TAGS
Add vmalloc tagging support to HW_TAGS KASAN. The key difference between HW_TAGS and the other two KASAN modes when it comes to vmalloc: HW_TAGS KASAN can only assign tags to physical memory. The other two modes have shadow memory covering every mapped virtual memory region. Make __kasan_unpoison_vmalloc() for HW_TAGS KASAN: - Skip non-VM_ALLOC mappings as HW_TAGS KASAN can only tag a single mapping of normal physical memory; see the comment in the function. - Generate a random tag, tag the returned pointer and the allocation, and initialize the allocation at the same time. - Propagate the tag into the page stucts to allow accesses through page_address(vmalloc_to_page()). The rest of vmalloc-related KASAN hooks are not needed: - The shadow-related ones are fully skipped. - __kasan_poison_vmalloc() is kept as a no-op with a comment. Poisoning and zeroing of physical pages that are backing vmalloc() allocations are skipped via __GFP_SKIP_KASAN_UNPOISON and __GFP_SKIP_ZERO: __kasan_unpoison_vmalloc() does that instead. Enabling CONFIG_KASAN_VMALLOC with HW_TAGS is not yet allowed. Link: https://lkml.kernel.org/r/d19b2e9e59a9abc59d05b72dea8429dcaea739c6.1643047180.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Co-developed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Acked-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/kasan/shadow.c')
-rw-r--r--mm/kasan/shadow.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 5a866f6663fc..b958babc8fed 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -475,8 +475,16 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end,
}
}
-void *__kasan_unpoison_vmalloc(const void *start, unsigned long size)
+void *__kasan_unpoison_vmalloc(const void *start, unsigned long size,
+ kasan_vmalloc_flags_t flags)
{
+ /*
+ * Software KASAN modes unpoison both VM_ALLOC and non-VM_ALLOC
+ * mappings, so the KASAN_VMALLOC_VM_ALLOC flag is ignored.
+ * Software KASAN modes can't optimize zeroing memory by combining it
+ * with setting memory tags, so the KASAN_VMALLOC_INIT flag is ignored.
+ */
+
if (!is_vmalloc_or_module_addr(start))
return (void *)start;