[PATCH v2 5/6] cio: ensure the copied buf is NUL terminated

Bui Quang Minh
2024-04-24T14:45:28Z

Currently, we allocate a lbuf-sized kernel buffer and copy lbuf from
userspace to that buffer. Later, we use scanf on this buffer but we don't
ensure that the string is terminated inside the buffer, this can lead to
OOB read when using scanf. Fix this issue by using memdup_user_nul instead.

Fixes: a4f17cc72671 ("s390/cio: add CRW inject functionality")
Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
---
drivers/s390/cio/cio_inject.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/s390/cio/cio_inject.c b/drivers/s390/cio/cio_inject.c
index 8613fa937237..a2e771ebae8e 100644
--- a/drivers/s390/cio/cio_inject.c
+++ b/drivers/s390/cio/cio_inject.c
@@ -95,7 +95,7 @@ static ssize_t crw_inject_write(struct file *file, const char __user *buf,
return -EINVAL;
}

- buffer = vmemdup_user(buf, lbuf);
+ buffer = memdup_user_nul(buf, lbuf);
if (IS_ERR(buffer))
return -ENOMEM;

--
2.34.1