From 130be64399dd18a268e28207a1e7029fb6713234 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 10 May 2024 07:29:32 +0000
Subject: [PATCH] inet: fix inet_fill_ifaddr() flags truncation
[ Upstream commit 1af7f88af269c4e06a4dc3bc920ff6cdf7471124 ]
I missed that (struct ifaddrmsg)->ifa_flags was only 8bits,
while (struct in_ifaddr)->ifa_flags is 32bits.
Use a temporary 32bit variable as I did in set_ifa_lifetime()
and check_lifetime().
Fixes: 3ddc2231c810 ("inet: annotate data-races around ifa->ifa_flags")
Reported-by: Yu Watanabe <watanabe.yu@gmail.com>
Dianosed-by: Yu Watanabe <watanabe.yu@gmail.com>
Closes: https://github.com/systemd/systemd/pull/32666#issuecomment-2103977928
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Larysa Zaremba <larysa.zaremba@intel.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240510072932.2678952-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/devinet.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 7a437f0d4190..7e45c34c8340 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1683,6 +1683,7 @@ static int inet_fill_ifaddr(struct sk_buff *skb, const struct in_ifaddr *ifa,
struct nlmsghdr *nlh;
unsigned long tstamp;
u32 preferred, valid;
+ u32 flags;
nlh = nlmsg_put(skb, args->portid, args->seq, args->event, sizeof(*ifm),
args->flags);
@@ -1692,7 +1693,13 @@ static int inet_fill_ifaddr(struct sk_buff *skb, const struct in_ifaddr *ifa,
ifm = nlmsg_data(nlh);
ifm->ifa_family = AF_INET;
ifm->ifa_prefixlen = ifa->ifa_prefixlen;
- ifm->ifa_flags = READ_ONCE(ifa->ifa_flags);
+
+ flags = READ_ONCE(ifa->ifa_flags);
+ /* Warning : ifm->ifa_flags is an __u8, it holds only 8 bits.
+ * The 32bit value is given in IFA_FLAGS attribute.
+ */
+ ifm->ifa_flags = (__u8)flags;
+
ifm->ifa_scope = ifa->ifa_scope;
ifm->ifa_index = ifa->ifa_dev->dev->ifindex;
@@ -1701,7 +1708,7 @@ static int inet_fill_ifaddr(struct sk_buff *skb, const struct in_ifaddr *ifa,
goto nla_put_failure;
tstamp = READ_ONCE(ifa->ifa_tstamp);
- if (!(ifm->ifa_flags & IFA_F_PERMANENT)) {
+ if (!(flags & IFA_F_PERMANENT)) {
preferred = READ_ONCE(ifa->ifa_preferred_lft);
valid = READ_ONCE(ifa->ifa_valid_lft);
if (preferred != INFINITY_LIFE_TIME) {
@@ -1732,7 +1739,7 @@ static int inet_fill_ifaddr(struct sk_buff *skb, const struct in_ifaddr *ifa,
nla_put_string(skb, IFA_LABEL, ifa->ifa_label)) ||
(ifa->ifa_proto &&
nla_put_u8(skb, IFA_PROTO, ifa->ifa_proto)) ||
- nla_put_u32(skb, IFA_FLAGS, ifm->ifa_flags) ||
+ nla_put_u32(skb, IFA_FLAGS, flags) ||
(ifa->ifa_rt_priority &&
nla_put_u32(skb, IFA_RT_PRIORITY, ifa->ifa_rt_priority)) ||
put_cacheinfo(skb, READ_ONCE(ifa->ifa_cstamp), tstamp,