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maple_tree: fix allocation in mas_sparse_area()

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In the case of reverse allocation, mas->index and mas->last do not point
to the correct allocation range, which will cause users to get incorrect
allocation results, so fix it.  If the user does not use it in a specific
way, this bug will not be triggered.

This is a bug, but only VMA uses it now, the way VMA is used now will
not trigger it.  There is a possibility that a user will trigger it in
the future.

Also re-check whether the size is still satisfied after the lower bound
was increased, which is a corner case and is incorrect in previous
versions.

Link: https://lkml.kernel.org/r/20230419093625.99201-1-zhangpeng.00@bytedance.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Peng Zhang 2023-04-19 17:36:25 +08:00 committed by Andrew Morton
parent 53156443a3
commit 29ad6bb313
1 changed files with 20 additions and 21 deletions
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41
lib/maple_tree.c
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@ -5250,25 +5250,28 @@ static inline void mas_fill_gap(struct ma_state *mas, void *entry,
* @size: The size of the gap
* @fwd: Searching forward or back
*/
static inline void mas_sparse_area(struct ma_state *mas, unsigned long min,
static inline int mas_sparse_area(struct ma_state *mas, unsigned long min,
unsigned long max, unsigned long size, bool fwd)
{
unsigned long start = 0;
if (!unlikely(mas_is_none(mas)))
start++;
if (!unlikely(mas_is_none(mas)) && min == 0) {
min++;
/*
* At this time, min is increased, we need to recheck whether
* the size is satisfied.
*/
if (min > max || max - min + 1 < size)
return -EBUSY;
}
/* mas_is_ptr */
if (start < min)
start = min;
if (fwd) {
mas->index = start;
mas->last = start + size - 1;
return;
mas->index = min;
mas->last = min + size - 1;
} else {
mas->last = max;
mas->index = max - size + 1;
}
mas->index = max;
return 0;
}
/*
@ -5297,10 +5300,8 @@ int mas_empty_area(struct ma_state *mas, unsigned long min,
return -EBUSY;
/* Empty set */
if (mas_is_none(mas) || mas_is_ptr(mas)) {
mas_sparse_area(mas, min, max, size, true);
return 0;
}
if (mas_is_none(mas) || mas_is_ptr(mas))
return mas_sparse_area(mas, min, max, size, true);
/* The start of the window can only be within these values */
mas->index = min;
@ -5356,10 +5357,8 @@ int mas_empty_area_rev(struct ma_state *mas, unsigned long min,
}
/* Empty set. */
if (mas_is_none(mas) || mas_is_ptr(mas)) {
mas_sparse_area(mas, min, max, size, false);
return 0;
}
if (mas_is_none(mas) || mas_is_ptr(mas))
return mas_sparse_area(mas, min, max, size, false);
/* The start of the window can only be within these values. */
mas->index = min;