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authorAndrey Konovalov <andreyknvl@google.com>2021-02-25 17:20:23 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-26 09:41:03 -0800
commitd12d9ad816299052385bac351fad338a073121b3 (patch)
treedb54aa89690c94d390c02ed4a85d46be251f3cfa /mm/slab_common.c
parent26a5ca7a73be31f76c291465680517cde37051ca (diff)
downloadlinux-d12d9ad816299052385bac351fad338a073121b3.tar.bz2
kasan, mm: optimize krealloc poisoning
Currently, krealloc() always calls ksize(), which unpoisons the whole object including the redzone. This is inefficient, as kasan_krealloc() repoisons the redzone for objects that fit into the same buffer. This patch changes krealloc() instrumentation to use uninstrumented __ksize() that doesn't unpoison the memory. Instead, kasan_kreallos() is changed to unpoison the memory excluding the redzone. For objects that don't fit into the old allocation, this patch disables KASAN accessibility checks when copying memory into a new object instead of unpoisoning it. Link: https://lkml.kernel.org/r/9bef90327c9cb109d736c40115684fd32f49e6b0.1612546384.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Branislav Rankov <Branislav.Rankov@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Kevin Brodsky <kevin.brodsky@arm.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab_common.c')
-rw-r--r--mm/slab_common.c20
1 files changed, 14 insertions, 6 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 4aedb8455352..88e833986332 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1136,19 +1136,27 @@ static __always_inline void *__do_krealloc(const void *p, size_t new_size,
void *ret;
size_t ks;
- if (likely(!ZERO_OR_NULL_PTR(p)) && !kasan_check_byte(p))
- return NULL;
-
- ks = ksize(p);
+ /* Don't use instrumented ksize to allow precise KASAN poisoning. */
+ if (likely(!ZERO_OR_NULL_PTR(p))) {
+ if (!kasan_check_byte(p))
+ return NULL;
+ ks = kfence_ksize(p) ?: __ksize(p);
+ } else
+ ks = 0;
+ /* If the object still fits, repoison it precisely. */
if (ks >= new_size) {
p = kasan_krealloc((void *)p, new_size, flags);
return (void *)p;
}
ret = kmalloc_track_caller(new_size, flags);
- if (ret && p)
- memcpy(ret, p, ks);
+ if (ret && p) {
+ /* Disable KASAN checks as the object's redzone is accessed. */
+ kasan_disable_current();
+ memcpy(ret, kasan_reset_tag(p), ks);
+ kasan_enable_current();
+ }
return ret;
}