futex: Initialize futex_phash_new during fork().

During a hash resize operation the new private hash is stored in mm_struct::futex_phash_new if the current hash can not be immediately replaced. The new hash must not be copied during fork() into the new task. Doing so will lead to a double-free of the memory by the two tasks. Initialize the mm_struct::futex_phash_new during fork().

Sebastian Andrzej Siewior committed 1 year ago

Commit a24cc6c1 parent 86731a21 file · +1 −0Browse files

Showing the changes to include/linux (1 of 1 file). Show all

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include/linux/futex.h+1−0

@@ -89,6 +89,7 @@ void futex_hash_free(struct mm_struct *mm); · 88 unmodified lines
89	static inline void futex_mm_init(struct mm_struct *mm)	89	static inline void futex_mm_init(struct mm_struct *mm)
90	{	90	{
91	RCU_INIT_POINTER(mm->futex_phash, NULL);	91	RCU_INIT_POINTER(mm->futex_phash, NULL);
		92	mm->futex_phash_new = NULL;
92	mutex_init(&mm->futex_hash_lock);	93	mutex_init(&mm->futex_hash_lock);
93	}	94	}
94		95