[PATCH] mtd: mtdram: check offs and len in mtdram->erase

[Dongsheng Yang]

We should prevent user to erasing mtd device with
an unaligned offset or length.

Signed-off-by: Dongsheng Yang <yangds.fnst at cn.fujitsu.com>
---
 drivers/mtd/devices/mtdram.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/mtd/devices/mtdram.c b/drivers/mtd/devices/mtdram.c
index 8e28508..73fa297 100644
--- a/drivers/mtd/devices/mtdram.c
+++ b/drivers/mtd/devices/mtdram.c
@@ -32,8 +32,29 @@ MODULE_PARM_DESC(erase_size, "Device erase block size in KiB");
 // We could store these in the mtd structure, but we only support 1 device..
 static struct mtd_info *mtd_info;
 
+static int check_offs_len(struct mtd_info *mtd, loff_t ofs, uint64_t len)
+{
+	int ret = 0;
+
+	/* Start address must align on block boundary */
+	if (ofs % mtd->erasesize) {
+		pr_debug("%s: unaligned address\n", __func__);
+		ret = -EINVAL;
+	}
+
+	/* Length must align on block boundary */
+	if (len % mtd->erasesize) {
+		pr_debug("%s: length not block aligned\n", __func__);
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
 static int ram_erase(struct mtd_info *mtd, struct erase_info *instr)
 {
+	if (check_offs_len(mtd, instr->addr, instr->len))
+		return -EINVAL;
 	memset((char *)mtd->priv + instr->addr, 0xff, instr->len);
 	instr->state = MTD_ERASE_DONE;
 	mtd_erase_callback(instr);
-- 
1.8.4.2