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kcsan: Never set up watchpoints on NULL pointers

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Avoid setting up watchpoints on NULL pointers, as otherwise we would
crash inside the KCSAN runtime (when checking for value changes) instead
of the instrumented code.

Because that may be confusing, skip any address less than PAGE_SIZE.

Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Marco Elver 2020-10-22 13:45:53 +02:00 committed by Paul E. McKenney
parent 4761612ffe
commit 55a2346c7a
1 changed files with 5 additions and 1 deletions
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6
kernel/kcsan/encoding.h
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@ -48,7 +48,11 @@
static inline bool check_encodable(unsigned long addr, size_t size)
{
return size <= MAX_ENCODABLE_SIZE;
/*
* While we can encode addrs<PAGE_SIZE, avoid crashing with a NULL
* pointer deref inside KCSAN.
*/
return addr >= PAGE_SIZE && size <= MAX_ENCODABLE_SIZE;
}
static inline long