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

From: Dongsheng Yang
Date: Fri Oct 02 2015 - 05:45:42 EST


On 10/01/2015 12:41 AM, Sudip Mukherjee wrote:
We should prevent user to erasing mtd device with an unaligned offset
or length.

Signed-off-by: Sudip Mukherjee <sudip@xxxxxxxxxxxxxxx>
---

I am not sure if I should add the Signed-off-by of
Dongsheng Yang <yangds.fnst@xxxxxxxxxxxxxx> . He is the original author
and he should get the credit for that.

But I had sent a a patch out to fix this problem before your v1.

http://lists.infradead.org/pipermail/linux-mtd/2015-September/062234.html

Yang

drivers/mtd/devices/mtdram.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/drivers/mtd/devices/mtdram.c b/drivers/mtd/devices/mtdram.c
index 8e28508..21b6a05 100644
--- a/drivers/mtd/devices/mtdram.c
+++ b/drivers/mtd/devices/mtdram.c
@@ -32,8 +32,35 @@ 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;
+ uint64_t temp_len, rem;
+
+ /* Start address must align on block boundary */
+ temp_len = ofs;
+ rem = do_div(temp_len, mtd->erasesize);
+ if (rem) {
+ pr_debug("%s: unaligned address\n", __func__);
+ ret = -EINVAL;
+ }
+
+ /* Length must align on block boundary */
+ temp_len = len;
+ rem = do_div(temp_len, mtd->erasesize);
+
+ if (rem) {
+ 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);


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