6.5-stable review patch. If anyone has any objections, please let me know.
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From: Liam R. Howlett Liam.Howlett@oracle.com
[ Upstream commit 5c590804b6b0ff933ed4e5cee5d76de3a5048d9f ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/maple_tree.h | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h index 295548cca8b36..e1e5f38384b20 100644 --- a/include/linux/maple_tree.h +++ b/include/linux/maple_tree.h @@ -503,6 +503,15 @@ 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.