From: Jakub Kicinski <kuba@kernel.org>
To: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Patrick McHardy <kaber@trash.net>,
Pablo Neira Ayuso <pablo@netfilter.org>,
Christophe Ricard <christophe-h.ricard@st.com>,
Johannes Berg <johannes.berg@intel.com>,
David Ahern <dsahern@gmail.com>,
Kuniyuki Iwashima <kuni1840@gmail.com>, <netdev@vger.kernel.org>,
Brad Spencer <bspencer@blackberry.com>
Subject: Re: [PATCH v1 net] netlink: Use copy_to_user() for optval in netlink_getsockopt().
Date: Tue, 18 Apr 2023 20:33:18 -0700 [thread overview]
Message-ID: <20230418203318.2053c4f9@kernel.org> (raw)
In-Reply-To: <20230419004246.25770-1-kuniyu@amazon.com>
On Tue, 18 Apr 2023 17:42:46 -0700 Kuniyuki Iwashima wrote:
> Brad Spencer provided a detailed report that when calling getsockopt()
> for AF_NETLINK, some SOL_NETLINK options set only 1 byte even though such
> options require more than int as length.
>
> The options return a flag value that fits into 1 byte, but such behaviour
> confuses users who do not strictly check the value as char.
>
> Currently, netlink_getsockopt() uses put_user() to copy data to optlen and
> optval, but put_user() casts the data based on the pointer, char *optval.
> So, only 1 byte is set to optval.
>
> To avoid this behaviour, we need to use copy_to_user() or cast optval for
> put_user().
>
> Now getsockopt() accepts char as optval as the flags are only 1 byte.
I think it's worth doing, but it will change the return value on big
endian, right?
next prev parent reply other threads:[~2023-04-19 3:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-19 0:42 [PATCH v1 net] netlink: Use copy_to_user() for optval in netlink_getsockopt() Kuniyuki Iwashima
2023-04-19 3:33 ` Jakub Kicinski [this message]
2023-04-19 17:50 ` Kuniyuki Iwashima
2023-04-19 7:17 ` Johannes Berg
2023-04-19 17:52 ` Kuniyuki Iwashima
2023-04-19 19:46 ` Johannes Berg
2023-04-19 19:47 ` Johannes Berg
[not found] ` <20230419160908.5469e9bf@kernel.org>
2023-04-20 3:40 ` Kuniyuki Iwashima
2023-04-20 7:04 ` Johannes Berg
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