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([221.156.231.192]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c7921a12adasm12179185a12.26.2026.04.14.03.42.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2026 03:42:45 -0700 (PDT) From: DaeMyung Kang To: Mike Rapoport , Andrew Morton Cc: Masami Hiramatsu , Steven Rostedt , Donet Tom , stable@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, DaeMyung Kang Subject: [PATCH v2] mm/memblock: fix off-by-one page leak in reserve_mem_release_by_name() Date: Tue, 14 Apr 2026 19:42:36 +0900 Message-ID: <20260414104236.988942-1-charsyam@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 0E19740004 X-Stat-Signature: in81nyrfocxokwrxnudfdom57nycpx6d X-Rspam-User: X-HE-Tag: 1776163366-591963 X-HE-Meta: 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 fGbC64kF WXDMLJvueYpl7gRRP3byVbW/kZl+QAXqaOpJzqqRtutd9DJXRlBmOHLzqQJOqeg83KZK8pSeyN7scmPolOubaRQpBiYbV2ioZZAXZlRALzSO4ihrjCJWcYrx6vwq0MQlIQBVDfa5FS0rnhbSWPEy4fubCss2LShfhQWKjNRkU4TdI53UEiqOLqd2EChmZIMdV8151NoXDfRW8hw5TQ0Dcz6jkQcBgpP4rRnDIgxbb1Rce2O2ZW4pMbk2Rg50Uk60zBTHG4736iIGfEig33Y8DM5MeQgELMehsj0pnk1jA0ggPnHq72a/ui5ORJWGOI6UpuB9dCUiTk2c3+MEmR03GIePHnRmHE6UrLkIDUHVwp2bnGWN6xdBKNpZI6Aad8smXXiR1ZfY3QPxOTAZOCP4Vw8amgyGtahHDKR/MlbB4eM64GvChDDRNv2FF1u7PlMXN1P/0Tpj/l/OKZqLoWQlJcAj0+bVw70kTlLwhZqsc1lCBohk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: free_reserved_area() treats its 'end' argument as exclusive: it aligns end down via 'end & PAGE_MASK' and iterates with 'pos < end'. reserve_mem_release_by_name() instead passes 'start + map->size - 1', which causes the last page of a page-aligned reservation to never be freed. For a reservation spanning N pages, only N - 1 pages are released back to the allocator. Fix it by passing the exclusive end address, 'start + map->size'. Fixes: 74e2498ccf7b ("mm/memblock: Add reserved memory release function") Cc: stable@vger.kernel.org Signed-off-by: DaeMyung Kang --- Changes in v2: - Add Fixes: tag and Cc: stable (per Donet Tom's review). - v1: https://lore.kernel.org/lkml/ mm/memblock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memblock.c b/mm/memblock.c index b3ddfdec7a80..d4a02f1750e9 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -2434,7 +2434,7 @@ int reserve_mem_release_by_name(const char *name) return 0; start = phys_to_virt(map->start); - end = start + map->size - 1; + end = start + map->size; snprintf(buf, sizeof(buf), "reserve_mem:%s", name); free_reserved_area(start, end, 0, buf); map->size = 0; -- 2.43.0