If cma_activate_area() fails after allocating only part of the range
bitmaps, its cleanup path frees the bitmaps for the ranges below
allocrange and then releases reserved pages using the same bound.

That bound is only correct for bitmap freeing. Pages in ranges that did
not reach bitmap allocation are still reserved and should also be
returned to the buddy when CMA_RESERVE_PAGES_ON_ERROR is clear. As a
result, a partial bitmap allocation failure can permanently leak the
reserved pages from the failed range and all later ranges.

Fix this by releasing reserved pages for all ranges. For ranges whose
bitmap allocation succeeded, use the early_pfn[] snapshot saved before
the bitmap pointer overwrote the union field. For later ranges, continue
to use cmr->early_pfn directly.

Fixes: c009da4258f9 ("mm, cma: support multiple contiguous ranges, if requested")
Cc: stable@vger.kernel.org
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/cma.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/mm/cma.c b/mm/cma.c
index c7ca567f4c5c..a30075507d41 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -188,10 +188,13 @@ static void __init cma_activate_area(struct cma *cma)
 
 	/* Expose all pages to the buddy, they are useless for CMA. */
 	if (!test_bit(CMA_RESERVE_PAGES_ON_ERROR, &cma->flags)) {
-		for (r = 0; r < allocrange; r++) {
+		for (r = 0; r < cma->nranges; r++) {
+			unsigned long start_pfn;
+
 			cmr = &cma->ranges[r];
+			start_pfn = r < allocrange ? early_pfn[r] : cmr->early_pfn;
 			end_pfn = cmr->base_pfn + cmr->count;
-			for (pfn = early_pfn[r]; pfn < end_pfn; pfn++)
+			for (pfn = start_pfn; pfn < end_pfn; pfn++)
 				free_reserved_page(pfn_to_page(pfn));
 		}
 	}

base-commit: e98d21c170b01ddef366f023bbfcf6b31509fa83
-- 
2.54.0