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net-packet: fix null pointer exception in rollover mode 

Rollover can be enabled as flag or mode. Allocate state in both cases.
This solves a NULL pointer exception in fanout_demux_rollover on
referencing po->rollover if using mode rollover.

Also make sure that in rollover mode each silo is tried (contrary
to rollover flag, where the main socket is excluded after an initial
try_self).

Tested:
  Passes tools/testing/net/psock_fanout.c, which tests both modes and
  flag. My previous tests were limited to bench_rollover, which only
  stresses the flag. The test now completes safely. it still gives an
  error for mode rollover, because it does not expect the new headroom
  (ROOM_NORMAL) requirement. I will send a separate patch to the test.

Fixes: 0648ab70af ("packet: rollover prepare: per-socket state")

Signed-off-by: Willem de Bruijn <willemb@google.com>

----

I should have run this test and caught this before submission, of
course. Apologies for the oversight.
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Willem de Bruijn 2015-05-17 19:44:02 -04:00 committed by David S. Miller
parent c91d460652
commit 4633c9e07b
1 changed files with 5 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
net/packet/af_packet.c
View File

@ -1389,7 +1389,7 @@ static unsigned int fanout_demux_rollover(struct packet_fanout *f,
unsigned int idx, bool try_self,
unsigned int num)
{
struct packet_sock *po, *po_next;
struct packet_sock *po, *po_next, *po_skip = NULL;
unsigned int i, j, room = ROOM_NONE;
po = pkt_sk(f->arr[idx]);
@ -1399,12 +1399,13 @@ static unsigned int fanout_demux_rollover(struct packet_fanout *f,
if (room == ROOM_NORMAL ||
(room == ROOM_LOW && !fanout_flow_is_huge(po, skb)))
return idx;
po_skip = po;
}
i = j = min_t(int, po->rollover->sock, num - 1);
do {
po_next = pkt_sk(f->arr[i]);
if (po_next != po && !po_next->pressure &&
if (po_next != po_skip && !po_next->pressure &&
packet_rcv_has_room(po_next, skb) == ROOM_NORMAL) {
if (i != j)
po->rollover->sock = i;
@ -1549,7 +1550,8 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
if (po->fanout)
return -EALREADY;
if (type_flags & PACKET_FANOUT_FLAG_ROLLOVER) {
if (type == PACKET_FANOUT_ROLLOVER ||
(type_flags & PACKET_FANOUT_FLAG_ROLLOVER)) {
po->rollover = kzalloc(sizeof(*po->rollover), GFP_KERNEL);
if (!po->rollover)
return -ENOMEM;