| From | Herton Ronaldo Krzesinski <> | Subject | [PATCH 212/241] ipv4: avoid undefined behavior in do_ip_setsockopt() | Date | Thu, 13 Dec 2012 11:59:37 -0200 |
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3.5.7.2 -stable review patch. If anyone has any objections, please let me know.
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From: Xi Wang <xi.wang@gmail.com>
commit 0c9f79be295c99ac7e4b569ca493d75fdcc19e4e upstream.
(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: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.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 0d11f23..8285f00 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -456,19 +456,28 @@ 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; -- 1.7.9.5
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