cipso: adjust cached option offsets when removing CIPSO

cipso_v4_skbuff_delattr() removes the CIPSO bytes but does not adjust
cached offsets for options that follow them.

For example, with a valid 10-byte CIPSO option followed by a seven-byte
RR option, parsing records rr at offset 30.  Removing CIPSO moves RR to
offset 20, while the cached offset remains 30.  Consumers such as
ip_forward_options() and __ip_options_echo() then access the wrong bytes;
the latter may interpret packet data as the option length and copy it into
fixed-size option storage.

Mirror cipso_v4_delopt() and subtract cipso_len from the srr, rr, ts and
router_alert offsets when they follow CIPSO.  cipso_len is the distance
the first memmove() shifts those options.  The later header move and
network-header reset relocate the bytes and their offset base together.

Fixes: 89aa3619d141 ("cipso: make cipso_v4_skbuff_delattr() fully remove the CIPSO options")
Cc: stable@vger.kernel.org
Reviewed-by: Ondrej Mosnáček <omosnacek@gmail.com>
Signed-off-by: Daehyeon Ko <4ncienth@gmail.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Link: https://patch.msgid.link/20261006035108.3101440-1-4ncienth@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions