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authorEric Dumazet <edumazet@google.com>2023-06-29 16:41:50 +0000
committerDavid S. Miller <davem@davemloft.net>2023-07-03 09:25:02 +0100
commit998127cdb4699b9d470a9348ffe9f1154346be5f (patch)
tree36118a1e2a55304a29e7e4b51da01e488ade0b14 /net
parentc94683ed35ec33775e982af45a54723b7ab05851 (diff)
tcp: annotate data races in __tcp_oow_rate_limited()
request sockets are lockless, __tcp_oow_rate_limited() could be called on the same object from different cpus. This is harmless. Add READ_ONCE()/WRITE_ONCE() annotations to avoid a KCSAN report. Fixes: 4ce7e93cb3fe ("tcp: rate limit ACK sent by SYN_RECV request sockets") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_input.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6f072095211e..57c8af1859c1 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3590,8 +3590,11 @@ static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32
static bool __tcp_oow_rate_limited(struct net *net, int mib_idx,
u32 *last_oow_ack_time)
{
- if (*last_oow_ack_time) {
- s32 elapsed = (s32)(tcp_jiffies32 - *last_oow_ack_time);
+ /* Paired with the WRITE_ONCE() in this function. */
+ u32 val = READ_ONCE(*last_oow_ack_time);
+
+ if (val) {
+ s32 elapsed = (s32)(tcp_jiffies32 - val);
if (0 <= elapsed &&
elapsed < READ_ONCE(net->ipv4.sysctl_tcp_invalid_ratelimit)) {
@@ -3600,7 +3603,10 @@ static bool __tcp_oow_rate_limited(struct net *net, int mib_idx,
}
}
- *last_oow_ack_time = tcp_jiffies32;
+ /* Paired with the prior READ_ONCE() and with itself,
+ * as we might be lockless.
+ */
+ WRITE_ONCE(*last_oow_ack_time, tcp_jiffies32);
return false; /* not rate-limited: go ahead, send dupack now! */
}