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authorAndrey Konovalov <andreyknvl@google.com>2021-02-24 12:05:50 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-24 13:38:31 -0800
commit611806b4bf8dd97a4f3d73f5cf3c2c7730c51eb2 (patch)
treebc3e29573db25c2b8c21c03f03b5e9544aaa6013 /include
parent027b37b552f326aa94ef06c7ea77088b16c41e6e (diff)
kasan: fix bug detection via ksize for HW_TAGS mode
The currently existing kasan_check_read/write() annotations are intended to be used for kernel modules that have KASAN compiler instrumentation disabled. Thus, they are only relevant for the software KASAN modes that rely on compiler instrumentation. However there's another use case for these annotations: ksize() checks that the object passed to it is indeed accessible before unpoisoning the whole object. This is currently done via __kasan_check_read(), which is compiled away for the hardware tag-based mode that doesn't rely on compiler instrumentation. This leads to KASAN missing detecting some memory corruptions. Provide another annotation called kasan_check_byte() that is available for all KASAN modes. As the implementation rename and reuse kasan_check_invalid_free(). Use this new annotation in ksize(). To avoid having ksize() as the top frame in the reported stack trace pass _RET_IP_ to __kasan_check_byte(). Also add a new ksize_uaf() test that checks that a use-after-free is detected via ksize() itself, and via plain accesses that happen later. Link: https://linux-review.googlesource.com/id/Iaabf771881d0f9ce1b969f2a62938e99d3308ec5 Link: https://lkml.kernel.org/r/f32ad74a60b28d8402482a38476f02bb7600f620.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: 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 'include')
-rw-r--r--include/linux/kasan-checks.h6
-rw-r--r--include/linux/kasan.h17
2 files changed, 23 insertions, 0 deletions
diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
index ca5e89fb10d3..3d6d22a25bdc 100644
--- a/include/linux/kasan-checks.h
+++ b/include/linux/kasan-checks.h
@@ -5,6 +5,12 @@
#include <linux/types.h>
/*
+ * The annotations present in this file are only relevant for the software
+ * KASAN modes that rely on compiler instrumentation, and will be optimized
+ * away for the hardware tag-based KASAN mode. Use kasan_check_byte() instead.
+ */
+
+/*
* __kasan_check_*: Always available when KASAN is enabled. This may be used
* even in compilation units that selectively disable KASAN, but must use KASAN
* to validate access to an address. Never use these in header files!
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index a7254186558a..7eaf2d9effb4 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -246,6 +246,19 @@ static __always_inline void kasan_kfree_large(void *ptr)
__kasan_kfree_large(ptr, _RET_IP_);
}
+/*
+ * Unlike kasan_check_read/write(), kasan_check_byte() is performed even for
+ * the hardware tag-based mode that doesn't rely on compiler instrumentation.
+ */
+bool __kasan_check_byte(const void *addr, unsigned long ip);
+static __always_inline bool kasan_check_byte(const void *addr)
+{
+ if (kasan_enabled())
+ return __kasan_check_byte(addr, _RET_IP_);
+ return true;
+}
+
+
bool kasan_save_enable_multi_shot(void);
void kasan_restore_multi_shot(bool enabled);
@@ -301,6 +314,10 @@ static inline void *kasan_krealloc(const void *object, size_t new_size,
return (void *)object;
}
static inline void kasan_kfree_large(void *ptr) {}
+static inline bool kasan_check_byte(const void *address)
+{
+ return true;
+}
#endif /* CONFIG_KASAN */