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Commit 0c9f79be authored by Xi Wang's avatar Xi Wang Committed by David S. Miller
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ipv4: avoid undefined behavior in do_ip_setsockopt() 



(1<<optname) is undefined behavior in C with a negative optname or
optname larger than 31.  In those cases the result of the shift is
not necessarily zero (e.g., on x86).

This patch simplifies the code with a switch statement on optname.
It also allows the compiler to generate better code (e.g., using a
64-bit mask).

Signed-off-by: default avatarXi Wang <xi.wang@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 77b67063

net/ipv4/ip_sockglue.c

+22 −13
Original line number Diff line number Diff line
@@ -457,19 +457,28 @@ static int do_ip_setsockopt(struct sock *sk, int level, 
	struct inet_sock *inet = inet_sk(sk);

	int val = 0, err;



	if (((1<<optname) & ((1<<IP_PKTINFO) | (1<<IP_RECVTTL) |

			     (1<<IP_RECVOPTS) | (1<<IP_RECVTOS) |

			     (1<<IP_RETOPTS) | (1<<IP_TOS) |

			     (1<<IP_TTL) | (1<<IP_HDRINCL) |

			     (1<<IP_MTU_DISCOVER) | (1<<IP_RECVERR) |

			     (1<<IP_ROUTER_ALERT) | (1<<IP_FREEBIND) |

			     (1<<IP_PASSSEC) | (1<<IP_TRANSPARENT) |

			     (1<<IP_MINTTL) | (1<<IP_NODEFRAG))) ||

	    optname == IP_UNICAST_IF ||

	    optname == IP_MULTICAST_TTL ||

	    optname == IP_MULTICAST_ALL ||

	    optname == IP_MULTICAST_LOOP ||

	    optname == IP_RECVORIGDSTADDR) {

	switch (optname) {

	case IP_PKTINFO:

	case IP_RECVTTL:

	case IP_RECVOPTS:

	case IP_RECVTOS:

	case IP_RETOPTS:

	case IP_TOS:

	case IP_TTL:

	case IP_HDRINCL:

	case IP_MTU_DISCOVER:

	case IP_RECVERR:

	case IP_ROUTER_ALERT:

	case IP_FREEBIND:

	case IP_PASSSEC:

	case IP_TRANSPARENT:

	case IP_MINTTL:

	case IP_NODEFRAG:

	case IP_UNICAST_IF:

	case IP_MULTICAST_TTL:

	case IP_MULTICAST_ALL:

	case IP_MULTICAST_LOOP:

	case IP_RECVORIGDSTADDR:

		if (optlen >= sizeof(int)) {

			if (get_user(val, (int __user *) optval))

				return -EFAULT;