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    Subject[PATCH 5.15 091/167] ipv4: Fix data-races around sysctl_ip_dynaddr.
    Date
    From: Kuniyuki Iwashima <kuniyu@amazon.com>

    [ Upstream commit e49e4aff7ec19b2d0d0957ee30e93dade57dab9e ]

    While reading sysctl_ip_dynaddr, it can be changed concurrently.
    Thus, we need to add READ_ONCE() to its readers.

    Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
    Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    Documentation/networking/ip-sysctl.rst | 2 +-
    net/ipv4/af_inet.c | 4 ++--
    2 files changed, 3 insertions(+), 3 deletions(-)

    diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
    index 8d772484755a..b8b67041f955 100644
    --- a/Documentation/networking/ip-sysctl.rst
    +++ b/Documentation/networking/ip-sysctl.rst
    @@ -1157,7 +1157,7 @@ ip_autobind_reuse - BOOLEAN
    option should only be set by experts.
    Default: 0

    -ip_dynaddr - BOOLEAN
    +ip_dynaddr - INTEGER
    If set non-zero, enables support for dynamic addresses.
    If set to a non-zero value larger than 1, a kernel log
    message will be printed when dynamic address rewriting
    diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
    index 77534b44b8c7..44f21278003d 100644
    --- a/net/ipv4/af_inet.c
    +++ b/net/ipv4/af_inet.c
    @@ -1251,7 +1251,7 @@ static int inet_sk_reselect_saddr(struct sock *sk)
    if (new_saddr == old_saddr)
    return 0;

    - if (sock_net(sk)->ipv4.sysctl_ip_dynaddr > 1) {
    + if (READ_ONCE(sock_net(sk)->ipv4.sysctl_ip_dynaddr) > 1) {
    pr_info("%s(): shifting inet->saddr from %pI4 to %pI4\n",
    __func__, &old_saddr, &new_saddr);
    }
    @@ -1306,7 +1306,7 @@ int inet_sk_rebuild_header(struct sock *sk)
    * Other protocols have to map its equivalent state to TCP_SYN_SENT.
    * DCCP maps its DCCP_REQUESTING state to TCP_SYN_SENT. -acme
    */
    - if (!sock_net(sk)->ipv4.sysctl_ip_dynaddr ||
    + if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_ip_dynaddr) ||
    sk->sk_state != TCP_SYN_SENT ||
    (sk->sk_userlocks & SOCK_BINDADDR_LOCK) ||
    (err = inet_sk_reselect_saddr(sk)) != 0)
    --
    2.35.1


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