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tipc: Fix minor bugs in link session number handling

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This patch introduces a new, out-of-range value to indicate that
a link endpoint does not have an existing session established
with its peer, eliminating the risk that the previously used
"invalid session number" value (i.e. zero) might eventually be
assigned as a valid session number and cause incorrect link
behavior.

The patch also introduces explicit bit masking when assigning a
new link session number to ensure it does not exceed 16 bits.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Allan Stephens 2008-06-04 17:29:39 -07:00 committed by David S. Miller
parent e0d4e3d0d7
commit a686e6859e
1 changed files with 12 additions and 5 deletions
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17
net/tipc/link.c
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@ -50,6 +50,12 @@
#include "bcast.h"
/*
* Out-of-range value for link session numbers
*/
#define INVALID_SESSION 0x10000
/*
* Limit for deferred reception queue:
*/
@ -464,7 +470,7 @@ struct link *tipc_link_create(struct bearer *b_ptr, const u32 peer,
msg = l_ptr->pmsg;
msg_init(msg, LINK_PROTOCOL, RESET_MSG, TIPC_OK, INT_H_SIZE, l_ptr->addr);
msg_set_size(msg, sizeof(l_ptr->proto_msg));
msg_set_session(msg, tipc_random);
msg_set_session(msg, (tipc_random & 0xffff));
msg_set_bearer_id(msg, b_ptr->identity);
strcpy((char *)msg_data(msg), if_name);
@ -705,10 +711,10 @@ void tipc_link_reset(struct link *l_ptr)
u32 checkpoint = l_ptr->next_in_no;
int was_active_link = tipc_link_is_active(l_ptr);
msg_set_session(l_ptr->pmsg, msg_session(l_ptr->pmsg) + 1);
msg_set_session(l_ptr->pmsg, ((msg_session(l_ptr->pmsg) + 1) & 0xffff));
/* Link is down, accept any session: */
l_ptr->peer_session = 0;
/* Link is down, accept any session */
l_ptr->peer_session = INVALID_SESSION;
/* Prepare for max packet size negotiation */
link_init_max_pkt(l_ptr);
@ -2275,7 +2281,8 @@ static void link_recv_proto_msg(struct link *l_ptr, struct sk_buff *buf)
switch (msg_type(msg)) {
case RESET_MSG:
if (!link_working_unknown(l_ptr) && l_ptr->peer_session) {
if (!link_working_unknown(l_ptr) &&
(l_ptr->peer_session != INVALID_SESSION)) {
if (msg_session(msg) == l_ptr->peer_session) {
dbg("Duplicate RESET: %u<->%u\n",
msg_session(msg), l_ptr->peer_session);