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Date: Sun, 11 Nov 2012 16:20:01 -0500
From: Xi Wang <xi.wang@...il.com>
To: "David S. Miller" <davem@...emloft.net>
Cc: netdev@...r.kernel.org, Xi Wang <xi.wang@...il.com>
Subject: [PATCH] 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@...il.com>
---
net/ipv4/ip_sockglue.c | 35 ++++++++++++++++++++++-------------
1 file changed, 22 insertions(+), 13 deletions(-)
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 5eea4a8..14bbfcf 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -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;
--
1.7.10.4
--
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