[PATCH v4 6/6] cxl/region: Reject poison scan for decoder without a partition

[Richard Cheng <icheng@nvidia.com>]

__cxl_dpa_reserve() may leave cxled->part at -1 when a decoder's DPA
range doesn't map to any reported partition, while still keeping
dpa_res. poison_by_decoder() then indexes cxlds->part[-1], causing an
out-of-bounds read when poison collection is triggered.

Return -ENODEV before accessing the partition array when no partition was
assigned.

Fixes: be5cbd084027 ("cxl: Kill enum cxl_decoder_mode")
Signed-off-by: Richard Cheng <icheng@nvidia.com>
---
 drivers/cxl/core/region.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index b7dc5d4988da..afe3fb57b7fe 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2954,6 +2954,8 @@ static int poison_by_decoder(struct device *dev, void *arg)
 	cxled = to_cxl_endpoint_decoder(dev);
 	if (!cxled->dpa_res)
 		return rc;
+	if (cxled->part < 0)
+		return -ENODEV;
 
 	cxlmd = cxled_to_memdev(cxled);
 	cxlds = cxlmd->cxlds;
-- 
2.43.0