linux-kernel - [PATCH 5.13 728/800] of: Fix truncation of memory sizes on 32-bit platforms

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Date:   Mon, 12 Jul 2021 08:12:31 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Rob Herring <robh@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.13 728/800] of: Fix truncation of memory sizes on 32-bit platforms

From: Geert Uytterhoeven <geert+renesas@...der.be>

[ Upstream commit 2892d8a00d23d511a0591ac4b2ff3f050ae1f004 ]

Variable "size" has type "phys_addr_t", which can be either 32-bit or
64-bit on 32-bit systems, while "unsigned long" is always 32-bit on
32-bit systems.  Hence the cast in

    (unsigned long)size / SZ_1M

may truncate a 64-bit size to 32-bit, as casts have a higher operator
precedence than divisions.

Fix this by inverting the order of the cast and division, which should
be safe for memory blocks smaller than 4 PiB.  Note that the division is
actually a shift, as SZ_1M is a power-of-two constant, hence there is no
need to use div_u64().

While at it, use "%lu" to format "unsigned long".

Fixes: e8d9d1f5485b52ec ("drivers: of: add initialization code for static reserved memory")
Fixes: 3f0c8206644836e4 ("drivers: of: add initialization code for dynamic reserved memory")
Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
Acked-by: Marek Szyprowski <m.szyprowski@...sung.com>
Link: https://lore.kernel.org/r/4a1117e72d13d26126f57be034c20dac02f1e915.1623835273.git.geert+renesas@glider.be
Signed-off-by: Rob Herring <robh@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/of/fdt.c             | 8 ++++----
 drivers/of/of_reserved_mem.c | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index ba17a80b8c79..cc71e0b3eed9 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -510,11 +510,11 @@ static int __init __reserved_mem_reserve_reg(unsigned long node,
 
 		if (size &&
 		    early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
-			pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %ld MiB\n",
-				uname, &base, (unsigned long)size / SZ_1M);
+			pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %lu MiB\n",
+				uname, &base, (unsigned long)(size / SZ_1M));
 		else
-			pr_info("Reserved memory: failed to reserve memory for node '%s': base %pa, size %ld MiB\n",
-				uname, &base, (unsigned long)size / SZ_1M);
+			pr_info("Reserved memory: failed to reserve memory for node '%s': base %pa, size %lu MiB\n",
+				uname, &base, (unsigned long)(size / SZ_1M));
 
 		len -= t_len;
 		if (first) {
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 15e2417974d6..3502ba522c39 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -134,9 +134,9 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
 			ret = early_init_dt_alloc_reserved_memory_arch(size,
 					align, start, end, nomap, &base);
 			if (ret == 0) {
-				pr_debug("allocated memory for '%s' node: base %pa, size %ld MiB\n",
+				pr_debug("allocated memory for '%s' node: base %pa, size %lu MiB\n",
 					uname, &base,
-					(unsigned long)size / SZ_1M);
+					(unsigned long)(size / SZ_1M));
 				break;
 			}
 			len -= t_len;
@@ -146,8 +146,8 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
 		ret = early_init_dt_alloc_reserved_memory_arch(size, align,
 							0, 0, nomap, &base);
 		if (ret == 0)
-			pr_debug("allocated memory for '%s' node: base %pa, size %ld MiB\n",
-				uname, &base, (unsigned long)size / SZ_1M);
+			pr_debug("allocated memory for '%s' node: base %pa, size %lu MiB\n",
+				uname, &base, (unsigned long)(size / SZ_1M));
 	}
 
 	if (base == 0) {
-- 
2.30.2