net/packet: check length in getsockopt() called with PACKET_HDRLEN
authorAlexander Potapenko <glider@google.com>
Tue, 25 Apr 2017 16:51:46 +0000 (18:51 +0200)
committerDavid S. Miller <davem@davemloft.net>
Tue, 25 Apr 2017 18:05:52 +0000 (14:05 -0400)
commitfd2c83b35752f0a8236b976978ad4658df14a59f
treec655f98ff56baaab4571e8eab59ab6d68fca67cd
parent8048ced9beb21a52e3305f3332ae82020619f24e
net/packet: check length in getsockopt() called with PACKET_HDRLEN

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@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/packet/af_packet.c