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locking/mutex: Add MUTEX_WARN_ON() into fast path

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Scenario: In platform_device_register, the driver misuses struct
device as platform_data, making kmemdup duplicate a device. Accessing
the duplicate may cause list corruption due to its mutex magic or list
holding old content.
It recurs randomly as the first mutex - getting process skips the slow
path and mutex check. Adding MUTEX_WARN_ON(lock->magic!= lock) in
__mutex_trylock_fast() makes it always happen.

Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250126033243.53069-1-cuiyunhui@bytedance.com
This commit is contained in:
Yunhui Cui 2025-01-26 11:32:43 +08:00 committed by Peter Zijlstra
parent 2d352ec9fc
commit 337369f8ce
1 changed files with 2 additions and 0 deletions
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kernel/locking/mutex.c
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@ -143,6 +143,8 @@ static __always_inline bool __mutex_trylock_fast(struct mutex *lock)
unsigned long curr = (unsigned long)current; unsigned long curr = (unsigned long)current;
unsigned long zero = 0UL; unsigned long zero = 0UL;
MUTEX_WARN_ON(lock->magic != lock);
if (atomic_long_try_cmpxchg_acquire(&lock->owner, &zero, curr)) if (atomic_long_try_cmpxchg_acquire(&lock->owner, &zero, curr))
return true; return true;