From: Willem de Bruijn willemb@google.com
[ Upstream commit ec6af094ea28f0f2dda1a6a33b14cd57e36a9755 ]
Packet sockets may switch ring versions. Avoid misinterpreting state between versions, whose fields share a union. rx_owner_map is only allocated with a packet ring (pg_vec) and both are swapped together. If pg_vec is NULL, meaning no packet ring was allocated, then neither was rx_owner_map. And the field may be old state from a tpacket_v3.
Fixes: 61fad6816fc1 ("net/packet: tpacket_rcv: avoid a producer race condition") Reported-by: Syzbot syzbot+1ac0994a0a0c55151121@syzkaller.appspotmail.com Signed-off-by: Willem de Bruijn willemb@google.com Reviewed-by: Eric Dumazet edumazet@google.com Link: https://lore.kernel.org/r/20211215143937.106178-1-willemdebruijn.kernel@gmai... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/packet/af_packet.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 50ca70b3c1759..3177b9320c62d 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -4477,9 +4477,10 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, }
out_free_pg_vec: - bitmap_free(rx_owner_map); - if (pg_vec) + if (pg_vec) { + bitmap_free(rx_owner_map); free_pg_vec(pg_vec, order, req->tp_block_nr); + } out: return err; }