[PATCH net-next] ipv6: initialize ipcm6_cookie before parsing control messages

[Fernando Fernandez Mancera]

On Thu, 09 Jul 2026 16:32:30 +0800, Wayen Yan <win847 at gmail.com> wrote:
> ip6_datagram_send_ctl() parses both SOL_IPV6 and SOL_SOCKET control
> messages. For SOL_SOCKET messages it passes ipc6->sockc to
> __sock_cmsg_send(), which updates fields such as tsflags with
> read-modify-write operations.
> 
> The IPV6_2292PKTOPTIONS and flowlabel option paths only set ipc6.opt
> before calling ip6_datagram_send_ctl(). If a SOL_SOCKET control message
> such as SO_TIMESTAMPING_* or SCM_TS_OPT_ID is present, this can read
> uninitialized sockc state.
> 
> Initialize the ipcm6_cookie with ipcm6_init_sk(), as the normal IPv6
> sendmsg paths do, before overriding ->opt with the temporary option
> buffer.
> 
> Signed-off-by: Wayen Yan <win847 at gmail.com>
>

Reviewed-by: Fernando Fernandez Mancera <fmancera at suse.de>

Thanks!