net: hsr: fix potential OOB access in supervision frame handling

net: hsr: fix potential OOB access in supervision frame handling

Ensure the entire TLV header is linearized before access by adding
sizeof(struct hsr_sup_tlv) to the pskb_may_pull() calls. Without this,
a truncated frame could cause an out-of-bounds access.

Fixes: eafaa88b3eb7 ("net: hsr: Add support for redbox supervision frames")
Signed-off-by: Luka Gejak <luka.gejak@linux.dev>
Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>
Link: https://patch.msgid.link/20260523130330.61880-1-luka.gejak@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>