The problem is that "erasesize" is a uint32_t type so it might be
non-zero but the truncated "(uint32_t)erasesize" value *is* zero. That
would lead to the divide by zero bug.
Avoid the bug by delaying the divide until after we have validated
that "erasesize" is reasonable.
Fixes: dc2b3e5cbc80 ("mtd: phram: use div_u64_rem to stop overwrite len in phram_setup")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
drivers/mtd/devices/phram.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
index 6ed6c51fac69..d503821a3e60 100644
--- a/drivers/mtd/devices/phram.c
+++ b/drivers/mtd/devices/phram.c
@@ -264,16 +264,20 @@ static int phram_setup(const char *val)
}
}
- if (erasesize)
- div_u64_rem(len, (uint32_t)erasesize, &rem);
-
if (len == 0 || erasesize == 0 || erasesize > len
- || erasesize > UINT_MAX || rem) {
+ || erasesize > UINT_MAX) {
parse_err("illegal erasesize or len\n");
ret = -EINVAL;
goto error;
}
+ div_u64_rem(len, (uint32_t)erasesize, &rem);
+ if (rem) {
+ parse_err("len is not multiple of erasesize\n");
+ ret = -EINVAL;
+ goto error;
+ }
+
ret = register_device(name, start, len, (uint32_t)erasesize);
if (ret)
goto error;
--
2.20.1
