On 2020-12-01 16:15, Dan Carpenter wrote:
The .x25_addr[] address comes from the user and is not necessarily
NUL terminated. This leads to a couple problems. The first problem is
that the strlen() in x25_bind() can read beyond the end of the buffer.
The second problem is more subtle and could result in memory
corruption.
The call tree is:
x25_connect()
--> x25_write_internal()
--> x25_addr_aton()
The .x25_addr[] buffers are copied to the "addresses" buffer from
x25_write_internal() so it will lead to stack corruption.
Verify that the strings are NUL terminated and return -EINVAL if they
are not.
Reported-by: "kiyin(尹亮)" <kiyin@xxxxxxxxxxx>
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
The first patch put a NUL terminator on the end of the string and this
patch returns an error instead. I don't have a strong preference,
which
patch to go with.
net/x25/af_x25.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index 9232cdb42ad9..d41fffb2507b 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -675,7 +675,8 @@ static int x25_bind(struct socket *sock, struct
sockaddr *uaddr, int addr_len)
int len, i, rc = 0;
if (addr_len != sizeof(struct sockaddr_x25) ||
- addr->sx25_family != AF_X25) {
+ addr->sx25_family != AF_X25 ||
+ strnlen(addr->sx25_addr.x25_addr, X25_ADDR_LEN) == X25_ADDR_LEN)
{
rc = -EINVAL;
goto out;
}
@@ -769,7 +770,8 @@ static int x25_connect(struct socket *sock, struct
sockaddr *uaddr,
rc = -EINVAL;
if (addr_len != sizeof(struct sockaddr_x25) ||
- addr->sx25_family != AF_X25)
+ addr->sx25_family != AF_X25 ||
+ strnlen(addr->sx25_addr.x25_addr, X25_ADDR_LEN) == X25_ADDR_LEN)
goto out;
rc = -ENETUNREACH;
Acked-by: Martin Schiller <ms@xxxxxxxxxx>
