From: Willy Tarreau w@1wt.eu
stable inclusion from stable-v5.10.125 commit 7ccb026ecb997405b59d391140c25ee347891504 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6EY
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit e8161345ddbb66e449abde10d2fdce93f867eba9 upstream.
In commit 190cc82489f4 ("tcp: change source port randomizarion at connect() time"), the table_perturb[] array was introduced and an index was taken from the port_offset via hash_32(). But it turns out that hash_32() performs a multiplication while the input here comes from the output of SipHash in secure_seq, that is well distributed enough to avoid the need for yet another hash.
Suggested-by: Amit Klein aksecurity@gmail.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: Willy Tarreau w@1wt.eu Signed-off-by: Jakub Kicinski kuba@kernel.org Cc: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Reviewed-by: Wei Li liwei391@huawei.com --- net/ipv4/inet_hashtables.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 72716d1a06e4..31b4196ea7e1 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -778,7 +778,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
net_get_random_once(table_perturb, INET_TABLE_PERTURB_SIZE * sizeof(*table_perturb)); - index = hash_32(port_offset, INET_TABLE_PERTURB_SHIFT); + index = port_offset & (INET_TABLE_PERTURB_SIZE - 1);
offset = READ_ONCE(table_perturb[index]) + (port_offset >> 32); offset %= remaining;