[PATCH 5.4 26/71] inetpeer: Fix data-races around sysctl.

Greg Kroah-Hartman
2022-07-19T12:11:13Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 3d32edf1f3c38d3301f6434e56316f293466d7fb ]

While reading inetpeer sysctl variables, they can be changed
concurrently. So, we need to add READ_ONCE() to avoid data-races.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/inetpeer.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index ff327a62c9ce..a18668552d33 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -148,16 +148,20 @@ static void inet_peer_gc(struct inet_peer_base *base,
struct inet_peer *gc_stack[],
unsigned int gc_cnt)
{
+ int peer_threshold, peer_maxttl, peer_minttl;
struct inet_peer *p;
__u32 delta, ttl;
int i;

- if (base->total >= inet_peer_threshold)
+ peer_threshold = READ_ONCE(inet_peer_threshold);
+ peer_maxttl = READ_ONCE(inet_peer_maxttl);
+ peer_minttl = READ_ONCE(inet_peer_minttl);
+
+ if (base->total >= peer_threshold)
ttl = 0; /* be aggressive */
else
- ttl = inet_peer_maxttl
- - (inet_peer_maxttl - inet_peer_minttl) / HZ *
- base->total / inet_peer_threshold * HZ;
+ ttl = peer_maxttl - (peer_maxttl - peer_minttl) / HZ *
+ base->total / peer_threshold * HZ;
for (i = 0; i < gc_cnt; i++) {
p = gc_stack[i];

--
2.35.1