diff options
| author | Guillaume Nault <gnault@redhat.com> | 2019-12-06 12:38:49 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-12-06 21:05:14 -0800 |
| commit | 721c8dafad26ccfa90ff659ee19755e3377b829d (patch) | |
| tree | 725d07517fb3ffada269bee3a5c69861c6a831c8 | |
| parent | cb44a08f8647fd2e8db5cc9ac27cd8355fa392d8 (diff) | |
tcp: Protect accesses to .ts_recent_stamp with {READ,WRITE}_ONCE()
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@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/net/tcp.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h index 43e04e14c41e..86b9a8766648 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -501,9 +501,9 @@ static inline void tcp_synq_overflow(const struct sock *sk) } } - 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? */ @@ -524,7 +524,7 @@ static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) } } - 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 |