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| author | Guillaume Nault <gnault@redhat.com> | 2019-12-06 12:38:49 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-18 16:05:53 +0100 |
| commit | d317809e23c78ea04677883f56e562211dc774d3 (patch) | |
| tree | 954485864e385481e04c25f9d1ac3d9e463020ac | |
| parent | e0082abd58708e23d510ab3967a831620f9b2153 (diff) | |
| download | linux-stable-d317809e23c78ea04677883f56e562211dc774d3.tar.gz linux-stable-d317809e23c78ea04677883f56e562211dc774d3.tar.bz2 linux-stable-d317809e23c78ea04677883f56e562211dc774d3.zip | |
tcp: Protect accesses to .ts_recent_stamp with {READ,WRITE}_ONCE()
[ 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@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 c1fad1b4c91b..09910641fcc3 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -491,9 +491,9 @@ 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? */ @@ -514,7 +514,7 @@ 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 |