[PATCH v14 08/16] cxl: Reject overflowing HDM decoder ranges

[Srirangan Madhavan <smadhavan@nvidia.com>]

An HDM decoder with a nonzero size can report a base and size whose end
address wraps the 64-bit address space. Reject that programming before
publishing the decoder range, so enumeration and later reset handling
cannot use the wrapped range.

Use check_add_overflow() for nonzero ranges. Preserve the existing
empty-range representation for zero-size decoders.

Signed-off-by: Srirangan Madhavan <smadhavan@nvidia.com>
---
 drivers/cxl/core/resource.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/resource.c b/drivers/cxl/core/resource.c
index 8dfeb12de8c9..8d2fbc49a06f 100644
--- a/drivers/cxl/core/resource.c
+++ b/drivers/cxl/core/resource.c
@@ -115,16 +115,21 @@ int cxl_hdm_unpack_decoder(struct cxl_decoder_settings *settings, int id,
 	int interleave_ways;
 	unsigned long flags = 0;
 	struct range hpa_range;
+	u64 end;
 	int rc;
 
 	if (!committed)
 		size = 0;
 	if (base == U64_MAX || size == U64_MAX)
 		return -ENXIO;
+	if (size && check_add_overflow(base, size - 1, &end))
+		return -ENXIO;
+	if (!size)
+		end = base - 1;
 
 	hpa_range = (struct range) {
 		.start = base,
-		.end = base + size - 1,
+		.end = end,
 	};
 
 	if (committed) {
-- 
2.43.0