net/packet: avoid truncating TPACKET_V3 private size

tpacket_req3.tp_sizeof_priv is an unsigned int, and packet_set_ring()
validates the full value against the block size.  init_prb_bdqc() then
stores it in the unsigned short blk_sizeof_priv field.

Commit 2b6867c2ce76 ("net/packet: fix overflow in check for priv area
size") fixed the validation arithmetic, but an accepted value above
USHRT_MAX still narrows when it is stored.

For a 131072-byte block, tp_sizeof_priv=65536 is valid.  The narrowing
makes offset_to_first_pkt 48 instead of 65584, so packet records can be
placed in the private area that userspace asked the kernel to preserve.

blk_sizeof_priv is internal state, so widen it to hold the validated
UAPI value.

Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.")
Cc: stable@vger.kernel.org
Signed-off-by: Mark Amirkan <markdamirkan@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260913-b4-send-packet-private-v1-1-925eab2cd388@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions