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Message-Id: <20191219182912.205576955@linuxfoundation.org>
Date: Thu, 19 Dec 2019 19:34:28 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Guillaume Nault <gnault@...hat.com>,
Eric Dumazet <edumazet@...gle.com>,
"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.19 14/47] tcp: Protect accesses to .ts_recent_stamp with {READ,WRITE}_ONCE()
From: Guillaume Nault <gnault@...hat.com>
[ Upstream commit 721c8dafad26ccfa90ff659ee19755e3377b829d ]
Syncookies borrow the ->rx_opt.ts_recent_stamp field to store the
timestamp of the last synflood. Protect them with READ_ONCE() and
WRITE_ONCE() since reads and writes aren't serialised.
Use of .rx_opt.ts_recent_stamp for storing the synflood timestamp was
introduced by a0f82f64e269 ("syncookies: remove last_synq_overflow from
struct tcp_sock"). But unprotected accesses were already there when
timestamp was stored in .last_synq_overflow.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Guillaume Nault <gnault@...hat.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
include/net/tcp.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -492,9 +492,9 @@ static inline void tcp_synq_overflow(con
}
}
- last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
+ last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
if (!time_between32(now, last_overflow, last_overflow + HZ))
- tcp_sk(sk)->rx_opt.ts_recent_stamp = now;
+ WRITE_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp, now);
}
/* syncookies: no recent synqueue overflow on this listening socket? */
@@ -515,7 +515,7 @@ static inline bool tcp_synq_no_recent_ov
}
}
- last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
+ last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
/* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID,
* then we're under synflood. However, we have to use
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