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| author | Guillaume Nault <gnault@redhat.com> | 2019-12-06 12:38:49 +0100 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2020-02-11 20:03:56 +0000 |
| commit | 3b995856122c2bba50525892afa9ec3ee939768b (patch) | |
| tree | 8f1a53e231a54d85783003ad14a681d821ee53b3 | |
| parent | 043bceeefbd0550f8a31f1086eac8829f7cebf0d (diff) | |
| download | linux-3b995856122c2bba50525892afa9ec3ee939768b.tar.gz linux-3b995856122c2bba50525892afa9ec3ee939768b.tar.bz2 linux-3b995856122c2bba50525892afa9ec3ee939768b.zip | |
tcp: Protect accesses to .ts_recent_stamp with {READ,WRITE}_ONCE()
commit 721c8dafad26ccfa90ff659ee19755e3377b829d upstream.
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>
[bwh: Backported to 3.16: Use ACCESS_ONCE() instead of {READ,WRITE}_ONCE()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -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 4aab231b119c..417460d2b217 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -482,17 +482,17 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, */ static inline void tcp_synq_overflow(struct sock *sk) { - unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; + unsigned long last_overflow = ACCESS_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp); unsigned long now = jiffies; if (!time_between32(now, last_overflow, last_overflow + HZ)) - tcp_sk(sk)->rx_opt.ts_recent_stamp = now; + ACCESS_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp) = now; } /* syncookies: no recent synqueue overflow on this listening socket? */ static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) { - unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; + unsigned long last_overflow = ACCESS_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp); return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); } |