maple_tree: reduce user error potential

commit 50e81c82ad947045c7ed26ddc9acb17276b653b6 upstream.

When iterating, a user may operate on the tree and cause the maple state
to be altered and left in an unintuitive state.  Detect this scenario and
correct it by setting to the limit and invalidating the state.

Link: https://lkml.kernel.org/r/20230120162650.984577-4-Liam.Howlett@oracle.com
Cc: <Stable@vger.kernel.org>
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index e0a76f6368e4e452b305b561d02bc823405ad2b3..9a97bab901b68033ccbecb5c1b5a951592f6a943 100644 (file)
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -4736,6 +4736,11 @@ static inline void *mas_next_entry(struct ma_state *mas, unsigned long limit)
        unsigned long last;
        enum maple_type mt;
 
+       if (mas->index > limit) {
+               mas->index = mas->last = limit;
+               mas_pause(mas);
+               return NULL;
+       }
        last = mas->last;
 retry:
        offset = mas->offset;
@@ -4842,6 +4847,11 @@ static inline void *mas_prev_entry(struct ma_state *mas, unsigned long min)
 {
        void *entry;
 
+       if (mas->index < min) {
+               mas->index = mas->last = min;
+               mas_pause(mas);
+               return NULL;
+       }
 retry:
        while (likely(!mas_is_none(mas))) {
                entry = mas_prev_nentry(mas, min, mas->index);