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Commit fd2c83b3 authored by Alexander Potapenko's avatar Alexander Potapenko Committed by David S. Miller
Browse files

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: default avatarAlexander Potapenko <glider@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8048ced9

net/packet/af_packet.c

+2 −0
Original line number Diff line number Diff line
@@ -3836,6 +3836,8 @@ 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) {