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maple_tree: fix mas_empty_area_rev() lower bound validation

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mas_empty_area_rev() was not correctly validating the start of a gap
against the lower limit.  This could lead to the range starting lower than
the requested minimum.

Fix the issue by better validating a gap once one is found.

This commit also adds tests to the maple tree test suite for this issue
and tests the mas_empty_area() function for similar bound checking.

Link: https://lkml.kernel.org/r/20230111200136.1851322-1-Liam.Howlett@oracle.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216911
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: <amanieu@gmail.com>
  Link: https://lore.kernel.org/linux-mm/0b9f5425-08d4-8013-aa4c-e620c3b10bb2@leemhuis.info/
Tested-by: Holger Hoffsttte <holger@applied-asynchrony.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Liam Howlett 2023-01-11 20:02:07 +00:00 committed by Andrew Morton
parent 24b5308cf5
commit 7327e8111a
2 changed files with 97 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
lib/maple_tree.c
View File

@ -4887,7 +4887,7 @@ static bool mas_rev_awalk(struct ma_state *mas, unsigned long size)
unsigned long *pivots, *gaps;
void __rcu **slots;
unsigned long gap = 0;
unsigned long max, min, index;
unsigned long max, min;
unsigned char offset;
if (unlikely(mas_is_err(mas)))
@ -4909,8 +4909,7 @@ static bool mas_rev_awalk(struct ma_state *mas, unsigned long size)
min = mas_safe_min(mas, pivots, --offset);
max = mas_safe_pivot(mas, pivots, offset, type);
index = mas->index;
while (index <= max) {
while (mas->index <= max) {
gap = 0;
if (gaps)
gap = gaps[offset];
@ -4941,10 +4940,8 @@ static bool mas_rev_awalk(struct ma_state *mas, unsigned long size)
min = mas_safe_min(mas, pivots, offset);
}
if (unlikely(index > max)) {
mas_set_err(mas, -EBUSY);
return false;
}
if (unlikely((mas->index > max) || (size - 1 > max - mas->index)))
goto no_space;
if (unlikely(ma_is_leaf(type))) {
mas->offset = offset;
@ -4961,9 +4958,11 @@ static bool mas_rev_awalk(struct ma_state *mas, unsigned long size)
return false;
ascend:
if (mte_is_root(mas->node))
mas_set_err(mas, -EBUSY);
if (!mte_is_root(mas->node))
return false;
no_space:
mas_set_err(mas, -EBUSY);
return false;
}

89
lib/test_maple_tree.c
View File

@ -2517,6 +2517,91 @@ static noinline void check_bnode_min_spanning(struct maple_tree *mt)
mt_set_non_kernel(0);
}
static noinline void check_empty_area_window(struct maple_tree *mt)
{
unsigned long i, nr_entries = 20;
MA_STATE(mas, mt, 0, 0);
for (i = 1; i <= nr_entries; i++)
mtree_store_range(mt, i*10, i*10 + 9,
xa_mk_value(i), GFP_KERNEL);
/* Create another hole besides the one at 0 */
mtree_store_range(mt, 160, 169, NULL, GFP_KERNEL);
/* Check lower bounds that don't fit */
rcu_read_lock();
MT_BUG_ON(mt, mas_empty_area_rev(&mas, 5, 90, 10) != -EBUSY);
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area_rev(&mas, 6, 90, 5) != -EBUSY);
/* Check lower bound that does fit */
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area_rev(&mas, 5, 90, 5) != 0);
MT_BUG_ON(mt, mas.index != 5);
MT_BUG_ON(mt, mas.last != 9);
rcu_read_unlock();
/* Check one gap that doesn't fit and one that does */
rcu_read_lock();
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area_rev(&mas, 5, 217, 9) != 0);
MT_BUG_ON(mt, mas.index != 161);
MT_BUG_ON(mt, mas.last != 169);
/* Check one gap that does fit above the min */
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area_rev(&mas, 100, 218, 3) != 0);
MT_BUG_ON(mt, mas.index != 216);
MT_BUG_ON(mt, mas.last != 218);
/* Check size that doesn't fit any gap */
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area_rev(&mas, 100, 218, 16) != -EBUSY);
/*
* Check size that doesn't fit the lower end of the window but
* does fit the gap
*/
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area_rev(&mas, 167, 200, 4) != -EBUSY);
/*
* Check size that doesn't fit the upper end of the window but
* does fit the gap
*/
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area_rev(&mas, 100, 162, 4) != -EBUSY);
/* Check mas_empty_area forward */
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area(&mas, 0, 100, 9) != 0);
MT_BUG_ON(mt, mas.index != 0);
MT_BUG_ON(mt, mas.last != 8);
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area(&mas, 0, 100, 4) != 0);
MT_BUG_ON(mt, mas.index != 0);
MT_BUG_ON(mt, mas.last != 3);
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area(&mas, 0, 100, 11) != -EBUSY);
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area(&mas, 5, 100, 6) != -EBUSY);
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area(&mas, 0, 8, 10) != -EBUSY);
mas_reset(&mas);
mas_empty_area(&mas, 100, 165, 3);
mas_reset(&mas);
MT_BUG_ON(mt, mas_empty_area(&mas, 100, 163, 6) != -EBUSY);
rcu_read_unlock();
}
static DEFINE_MTREE(tree);
static int maple_tree_seed(void)
{
@ -2765,6 +2850,10 @@ static int maple_tree_seed(void)
check_bnode_min_spanning(&tree);
mtree_destroy(&tree);
mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
check_empty_area_window(&tree);
mtree_destroy(&tree);
#if defined(BENCH)
skip:
#endif