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Message-ID: <20230111200136.1851322-1-Liam.Howlett@oracle.com>
Date: Wed, 11 Jan 2023 20:02:07 +0000
From: Liam Howlett <liam.howlett@...cle.com>
To: "linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
"maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>
CC: Liam Howlett <liam.howlett@...cle.com>,
"stable@...r.kernel.org" <stable@...r.kernel.org>,
"amanieu@...il.com" <amanieu@...il.com>
Subject: [PATCH] maple_tree: Fix mas_empty_area_rev() lower bound validation
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.
Cc: stable@...r.kernel.org
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=216911
Reported-by: amanieu@...il.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Link: https://lore.kernel.org/linux-mm/0b9f5425-08d4-8013-aa4c-e620c3b10bb2@leemhuis.info/
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
lib/maple_tree.c | 17 ++++-----
lib/test_maple_tree.c | 89 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 97 insertions(+), 9 deletions(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 26e2045d3cda..b990ccea454e 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -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;
}
diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
index 497fc93ccf9e..ec847bf4dcb4 100644
--- a/lib/test_maple_tree.c
+++ b/lib/test_maple_tree.c
@@ -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
--
2.35.1
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