diff options
| author | Marco Elver <elver@google.com> | 2020-02-05 11:14:19 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-03-21 09:42:42 +0100 |
| commit | ed95f95c86cd53621103d865d62b5e1f96e60edb (patch) | |
| tree | 494951a23a0a3a22bccecb1de3ae460ee31cc1c0 /kernel/kcsan/core.c | |
| parent | 8cfbb04fae75260eae07ab8c74c1dcd44294d739 (diff) | |
kcsan: Fix 0-sized checks
Instrumentation of arbitrary memory-copy functions, such as user-copies,
may be called with size of 0, which could lead to false positives.
To avoid this, add a comparison in check_access() for size==0, which
will be optimized out for constant sized instrumentation
(__tsan_{read,write}N), and therefore not affect the common-case
fast-path.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/kcsan/core.c')
| -rw-r--r-- | kernel/kcsan/core.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c index e3c7d8f34f2f..82c2bef827d4 100644 --- a/kernel/kcsan/core.c +++ b/kernel/kcsan/core.c @@ -456,6 +456,13 @@ static __always_inline void check_access(const volatile void *ptr, size_t size, long encoded_watchpoint; /* + * Do nothing for 0 sized check; this comparison will be optimized out + * for constant sized instrumentation (__tsan_{read,write}N). + */ + if (unlikely(size == 0)) + return; + + /* * Avoid user_access_save in fast-path: find_watchpoint is safe without * user_access_save, as the address that ptr points to is only used to * check if a watchpoint exists; ptr is never dereferenced. |