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| author | Xi Wang <xi.wang@gmail.com> | 2012-11-11 11:20:01 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-11-11 17:53:13 -0500 |
| commit | 0c9f79be295c99ac7e4b569ca493d75fdcc19e4e (patch) | |
| tree | 86ac3ac72907079585afc43ec2a25edcb8bb051b /net | |
| parent | 77b67063bb6bce6d475e910d3b886a606d0d91f7 (diff) | |
| download | lwn-0c9f79be295c99ac7e4b569ca493d75fdcc19e4e.tar.gz lwn-0c9f79be295c99ac7e4b569ca493d75fdcc19e4e.zip | |
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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/ip_sockglue.c | 35 |
1 files changed, 22 insertions, 13 deletions
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 5eea4a811042..14bbfcf717ac 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; |