From: Alexander Potapenko <glider@xxxxxxxxxx> [ Upstream commit fd2c83b35752f0a8236b976978ad4658df14a59f ] 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: Sasha Levin <alexander.levin@xxxxxxxxxxx> --- 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 1c03d83edd7e..7effa07c4491 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3482,6 +3482,8 @@ 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) { -- 2.11.0