ipv4: fix IP ID reuse in ip_select_ident_segs()

ip_select_ident_segs() must put the first of the @segs reserved IP IDs
in iph->id, as GSO assigns id, id + 1, ..., id + segs - 1 to segments.

Commit f866fbc842de ("ipv4: fix data-races around inet->inet_id")
used atomic_add_return() for non-TCP sockets, which returns the first
ID of the next packet instead. Consecutive GSO packets can then reuse
IP IDs.

SCTP GSO is affected. Other callers use segs == 1, and only see
a harmless off-by-one (UDP GSO has a separate, older issue).

Use atomic_fetch_add() instead, like the TCP path.

Fixes: f866fbc842de ("ipv4: fix data-races around inet->inet_id")
Signed-off-by: Eric Dumazet <edumazet@kernel.org>
Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260930144018.1174068-2-edumazet@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions