[PATCH 1/1] cmd: avoid overflow in mtd_is_aligned_with_min_io_size

[Heinrich Schuchardt]

Multiplication of u32 factors has an u32 result even if an overflow occurs.
An overflow may occur in

	u64 data_off = page * mtd->writesize;

The size of the flash device may exceed 4 GiB.

Play it safe and use u64 consistently.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 cmd/mtd.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/cmd/mtd.c b/cmd/mtd.c
index eb6e2d6892..fb6e2bb047 100644
--- a/cmd/mtd.c
+++ b/cmd/mtd.c
@@ -33,11 +33,9 @@ static struct mtd_info *get_mtd_by_name(const char *name)
 	return mtd;
 }
 
-static uint mtd_len_to_pages(struct mtd_info *mtd, u64 len)
+static u64 mtd_len_to_pages(struct mtd_info *mtd, u64 len)
 {
-	do_div(len, mtd->writesize);
-
-	return len;
+	return lldiv(len, mtd->writesize);
 }
 
 static bool mtd_is_aligned_with_min_io_size(struct mtd_info *mtd, u64 size)
@@ -72,8 +70,7 @@ static void mtd_dump_device_buf(struct mtd_info *mtd, u64 start_off,
 {
 	bool has_pages = mtd->type == MTD_NANDFLASH ||
 		mtd->type == MTD_MLCNANDFLASH;
-	int npages = mtd_len_to_pages(mtd, len);
-	uint page;
+	u64 page, npages = mtd_len_to_pages(mtd, len);
 
 	if (has_pages) {
 		for (page = 0; page < npages; page++) {
@@ -251,12 +248,12 @@ static int do_mtd_io(struct cmd_tbl *cmdtp, int flag, int argc,
 		     char *const argv[])
 {
 	bool dump, read, raw, woob, write_empty_pages, has_pages = false;
-	u64 start_off, off, len, remaining, default_len;
+	u64 start_off, off, len, oob_len, remaining, default_len;
 	struct mtd_oob_ops io_op = {};
-	uint user_addr = 0, npages;
+	uint user_addr = 0;
+	u64 npages;
 	const char *cmd = argv[0];
 	struct mtd_info *mtd;
-	u32 oob_len;
 	u8 *buf;
 	int ret;
 
@@ -322,7 +319,7 @@ static int do_mtd_io(struct cmd_tbl *cmdtp, int flag, int argc,
 	}
 
 	if (has_pages)
-		printf("%s %lld byte(s) (%d page(s)) at offset 0x%08llx%s%s%s\n",
+		printf("%s %lld byte(s) (%lld page(s)) at offset 0x%08llx%s%s%s\n",
 		       read ? "Reading" : "Writing", len, npages, start_off,
 		       raw ? " [raw]" : "", woob ? " [oob]" : "",
 		       !read && write_empty_pages ? " [dontskipff]" : "");
-- 
2.40.1