From 9665d5d62487e8e7b1f546c00e11107155384b9a Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Fri, 1 Feb 2013 07:21:41 +0000 Subject: [PATCH] packet: fix leakage of tx_ring memory When releasing a packet socket, the routine packet_set_ring() is reused to free rings instead of allocating them. But when calling it for the first time, it fills req->tp_block_nr with the value of rb->pg_vec_len which in the second invocation makes it bail out since req->tp_block_nr is greater zero but req->tp_block_size is zero. This patch solves the problem by passing a zeroed auto-variable to packet_set_ring() upon each invocation from packet_release(). As far as I can tell, this issue exists even since 69e3c75 (net: TX_RING and packet mmap), i.e. the original inclusion of TX ring support into af_packet, but applies only to sockets with both RX and TX ring allocated, which is probably why this was unnoticed all the time. Signed-off-by: Phil Sutter Cc: Johann Baudy Cc: Daniel Borkmann Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- net/packet/af_packet.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index e639645e8fe..c111bd0e083 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2361,13 +2361,15 @@ static int packet_release(struct socket *sock) packet_flush_mclist(sk); - memset(&req_u, 0, sizeof(req_u)); - - if (po->rx_ring.pg_vec) + if (po->rx_ring.pg_vec) { + memset(&req_u, 0, sizeof(req_u)); packet_set_ring(sk, &req_u, 1, 0); + } - if (po->tx_ring.pg_vec) + if (po->tx_ring.pg_vec) { + memset(&req_u, 0, sizeof(req_u)); packet_set_ring(sk, &req_u, 1, 1); + } fanout_release(sk);