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| author | Liam R. Howlett <Liam.Howlett@oracle.com> | 2024-04-22 16:33:49 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-05-17 12:02:30 +0200 |
| commit | 6c9c7c1e63b198a8b979ad963eb21410f10ccb00 (patch) | |
| tree | ca5ecca2dd2bcbcea0eb4d3fe178dafcb8b14072 /lib | |
| parent | 6a911b8884c0f6b61760e9262720ec15d0c24cf3 (diff) | |
| download | linux-6c9c7c1e63b198a8b979ad963eb21410f10ccb00.tar.gz linux-6c9c7c1e63b198a8b979ad963eb21410f10ccb00.tar.bz2 linux-6c9c7c1e63b198a8b979ad963eb21410f10ccb00.zip | |
maple_tree: fix mas_empty_area_rev() null pointer dereference
commit 955a923d2809803980ff574270f81510112be9cf upstream.
Currently the code calls mas_start() followed by mas_data_end() if the
maple state is MA_START, but mas_start() may return with the maple state
node == NULL. This will lead to a null pointer dereference when checking
information in the NULL node, which is done in mas_data_end().
Avoid setting the offset if there is no node by waiting until after the
maple state is checked for an empty or single entry state.
A user could trigger the events to cause a kernel oops by unmapping all
vmas to produce an empty maple tree, then mapping a vma that would cause
the scenario described above.
Link: https://lkml.kernel.org/r/20240422203349.2418465-1-Liam.Howlett@oracle.com
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reported-by: Marius Fleischer <fleischermarius@gmail.com>
Closes: https://lore.kernel.org/lkml/CAJg=8jyuSxDL6XvqEXY_66M20psRK2J53oBTP+fjV5xpW2-R6w@mail.gmail.com/
Link: https://lore.kernel.org/lkml/CAJg=8jyuSxDL6XvqEXY_66M20psRK2J53oBTP+fjV5xpW2-R6w@mail.gmail.com/
Tested-by: Marius Fleischer <fleischermarius@gmail.com>
Tested-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/maple_tree.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 684689457d77..41ef91590761 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -5085,18 +5085,18 @@ int mas_empty_area_rev(struct ma_state *mas, unsigned long min, if (size == 0 || max - min < size - 1) return -EINVAL; - if (mas_is_start(mas)) { + if (mas_is_start(mas)) mas_start(mas); - mas->offset = mas_data_end(mas); - } else if (mas->offset >= 2) { - mas->offset -= 2; - } else if (!mas_rewind_node(mas)) { + else if ((mas->offset < 2) && (!mas_rewind_node(mas))) return -EBUSY; - } - /* Empty set. */ - if (mas_is_none(mas) || mas_is_ptr(mas)) + if (unlikely(mas_is_none(mas) || mas_is_ptr(mas))) return mas_sparse_area(mas, min, max, size, false); + else if (mas->offset >= 2) + mas->offset -= 2; + else + mas->offset = mas_data_end(mas); + /* The start of the window can only be within these values. */ mas->index = min; |