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authorLiam R. Howlett <Liam.Howlett@oracle.com>2023-09-21 14:12:35 -0400
committerAndrew Morton <akpm@linux-foundation.org>2023-09-29 17:20:46 -0700
commit5c590804b6b0ff933ed4e5cee5d76de3a5048d9f (patch)
treeeaba1036909d61a02ee8660c003f2271b154d75c
parent7ee29facd8a9c5a26079148e36bcf07141b3a6bc (diff)
maple_tree: add mas_is_active() to detect in-tree walks
Patch series "maple_tree: Fix mas_prev() state regression". Pedro Falcato retported an mprotect regression [1] which was bisected back to the iterator changes for maple tree. Root cause analysis showed the mas_prev() running off the end of the VMA space (previous from 0) followed by mas_find(), would skip the first value. This patchset introduces maple state underflow/overflow so the sequence of calls on the maple state will return what the user expects. Users who encounter this bug may see mprotect(), userfaultfd_register(), and mlock() fail on VMAs mapped with address 0. This patch (of 2): Instead of constantly checking each possibility of the maple state, create a fast path that will skip over checking unlikely states. Link: https://lkml.kernel.org/r/20230921181236.509072-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20230921181236.509072-2-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Cc: Pedro Falcato <pedro.falcato@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--include/linux/maple_tree.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index e41c70ac7744..f66f5f78f8cf 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -511,6 +511,15 @@ static inline bool mas_is_paused(const struct ma_state *mas)
return mas->node == MAS_PAUSE;
}
+/* Check if the mas is pointing to a node or not */
+static inline bool mas_is_active(struct ma_state *mas)
+{
+ if ((unsigned long)mas->node >= MAPLE_RESERVED_RANGE)
+ return true;
+
+ return false;
+}
+
/**
* mas_reset() - Reset a Maple Tree operation state.
* @mas: Maple Tree operation state.