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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: Xi Wang <xi.wang@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xi Wang 2012-11-11 11:20:01 +00:00 committed by David S. Miller
parent 77b67063bb
commit 0c9f79be29
1 changed files with 22 additions and 13 deletions
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35
net/ipv4/ip_sockglue.c
View File

@ -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;