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| author | Liam Howlett <liam.howlett@oracle.com> | 2023-01-11 20:02:07 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-01-31 16:44:07 -0800 |
| commit | 7327e8111adb315423035fb5233533016dfd3f2e (patch) | |
| tree | 0276d59dc69b7d37bb6d3231481216bdcdfaa533 /lib/maple_tree.c | |
| parent | 24b5308cf5ee9f52dd22f3af78a5b0cdc9d35e72 (diff) | |
| download | lwn-7327e8111adb315423035fb5233533016dfd3f2e.tar.gz lwn-7327e8111adb315423035fb5233533016dfd3f2e.zip | |
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.
Link: https://lkml.kernel.org/r/20230111200136.1851322-1-Liam.Howlett@oracle.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216911
Fixes: 54a611b60590 ("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>
Diffstat (limited to 'lib/maple_tree.c')
| -rw-r--r-- | lib/maple_tree.c | 17 |
1 files changed, 8 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; } |