[ 54/83] ipv4: avoid undefined behavior in do_ip_setsockopt()
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2012-11-22 22:37:48
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3.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xi Wang <xi.wang@gmail.com> [ Upstream commit 0c9f79be295c99ac7e4b569ca493d75fdcc19e4e ] (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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv4/ip_sockglue.c | 35 ++++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 13 deletions(-)
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c@@ -457,19 +457,28 @@ static int do_ip_setsockopt(struct sock 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;