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tcp: annotate data races in __tcp_oow_rate_limited()

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[ Upstream commit 998127cdb4699b9d470a9348ffe9f1154346be5f ]

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: 4ce7e93cb3 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Eric Dumazet 2023-06-29 16:41:50 +00:00 committed by Greg Kroah-Hartman
parent 73f512bedf
commit b785ba0acc
1 changed files with 9 additions and 3 deletions
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12
net/ipv4/tcp_input.c
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@ -3560,8 +3560,11 @@ 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, static bool __tcp_oow_rate_limited(struct net *net, int mib_idx,
u32 *last_oow_ack_time) u32 *last_oow_ack_time)
{ {
if (*last_oow_ack_time) { /* Paired with the WRITE_ONCE() in this function. */
s32 elapsed = (s32)(tcp_jiffies32 - *last_oow_ack_time); u32 val = READ_ONCE(*last_oow_ack_time);
if (val) {
s32 elapsed = (s32)(tcp_jiffies32 - val);
if (0 <= elapsed && if (0 <= elapsed &&
elapsed < READ_ONCE(net->ipv4.sysctl_tcp_invalid_ratelimit)) { elapsed < READ_ONCE(net->ipv4.sysctl_tcp_invalid_ratelimit)) {
@ -3570,7 +3573,10 @@ 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! */ return false; /* not rate-limited: go ahead, send dupack now! */
} }