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Subject[PATCH v1 net 16/16] ipv4: Fix a data-race around sysctl_fib_sync_mem.
Date
While reading sysctl_fib_sync_mem, it can be changed concurrently.  So, we
need to add READ_ONCE(). Then we can set proc_douintvec_minmax_lockless()
as the handler to mark it safe.

Fixes: 9ab948a91b2c ("ipv4: Allow amount of dirty memory from fib resizing to be controllable")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
CC: David Ahern <dsahern@gmail.com>
---
net/ipv4/fib_trie.c | 2 +-
net/ipv4/sysctl_net_ipv4.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 2734c3af7e24..46e8a5125853 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -498,7 +498,7 @@ static void tnode_free(struct key_vector *tn)
tn = container_of(head, struct tnode, rcu)->kv;
}

- if (tnode_free_size >= sysctl_fib_sync_mem) {
+ if (tnode_free_size >= READ_ONCE(sysctl_fib_sync_mem)) {
tnode_free_size = 0;
synchronize_rcu();
}
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 3b1d18be0857..7ea681df37c4 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -578,7 +578,7 @@ static struct ctl_table ipv4_table[] = {
.data = &sysctl_fib_sync_mem,
.maxlen = sizeof(sysctl_fib_sync_mem),
.mode = 0644,
- .proc_handler = proc_douintvec_minmax,
+ .proc_handler = proc_douintvec_minmax_lockless,
.extra1 = &sysctl_fib_sync_mem_min,
.extra2 = &sysctl_fib_sync_mem_max,
},
--
2.30.2
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