From: Alexander Potapenko <glider@xxxxxxxxxx>
commit fd2c83b35752f0a8236b976978ad4658df14a59f upstream.
In the case getsockopt() is called with PACKET_HDRLEN and optlen < 4
|val| remains uninitialized and the syscall may behave differently
depending on its value, and even copy garbage to userspace on certain
architectures. To fix this we now return -EINVAL if optlen is too small.
This bug has been detected with KMSAN.
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
net/packet/af_packet.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 0bbb347..b915d01 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3338,6 +3338,8 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
case PACKET_HDRLEN:
if (len > sizeof(int))
len = sizeof(int);
+ if (len < sizeof(int))
+ return -EINVAL;
if (copy_from_user(&val, optval, len))
return -EFAULT;
switch (val) {
--
2.8.0.rc2.1.gbe9624a