Received-SPF: pass (google.com: domain of linux-kernel+bounces-593-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
From: Yuntao Wang <ytcoode@gmail.com>
To: linux-kernel@vger.kernel.org,
	kexec@lists.infradead.org,
	x86@kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Eric Biederman <ebiederm@xmission.com>,
	Yuntao Wang <ytcoode@gmail.com>
Subject: [PATCH 2/3] kexec_file: fix incorrect temp_start value in locate_mem_hole_top_down()
Date: Fri, 15 Dec 2023 16:09:09 +0800
Message-ID: <20231215080910.173338-3-ytcoode@gmail.com>
In-Reply-To: <20231215080910.173338-1-ytcoode@gmail.com>
References: <20231215080910.173338-1-ytcoode@gmail.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

temp_end represents the address of the last available byte. Therefore, the
starting address of the memory segment with temp_end as its last available
byte and a size of `kbuf->memsz`, that is, the value of temp_start, should
be `temp_end - kbuf->memsz + 1` instead of `temp_end - kbuf->memsz`.

Additionally, use the ALIGN_DOWN macro instead of open-coding it directly
in locate_mem_hole_top_down() to improve code readability.

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
---
 kernel/kexec_file.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 26be070d3bdd..c3bf52a9a8ad 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -426,11 +426,11 @@ static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
 	unsigned long temp_start, temp_end;
 
 	temp_end = min(end, kbuf->buf_max);
-	temp_start = temp_end - kbuf->memsz;
+	temp_start = temp_end - kbuf->memsz + 1;
 
 	do {
 		/* align down start */
-		temp_start = temp_start & (~(kbuf->buf_align - 1));
+		temp_start = ALIGN_DOWN(temp_start, kbuf->buf_align);
 
 		if (temp_start < start || temp_start < kbuf->buf_min)
 			return 0;
-- 
2.43.0