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bridge: Clamp forward_delay when enabling STP 

At some point limits were added to forward_delay.  However, the
limits are only enforced when STP is enabled.  This created a
scenario where you could have a value outside the allowed range
while STP is disabled, which then stuck around even after STP
is enabled.

This patch fixes this by clamping the value when we enable STP.

I had to move the locking around a bit to ensure that there is
no window where someone could insert a value outside the range
while we're in the middle of enabling STP.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Cheers,
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2013-09-12 17:12:05 +10:00 committed by David S. Miller
parent 9a0620133c
commit be4f154d5e
3 changed files with 30 additions and 12 deletions
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1
net/bridge/br_private.h
View File

@ -746,6 +746,7 @@ extern struct net_bridge_port *br_get_port(struct net_bridge *br,
extern void br_init_port(struct net_bridge_port *p);
extern void br_become_designated_port(struct net_bridge_port *p);
extern void __br_set_forward_delay(struct net_bridge *br, unsigned long t);
extern int br_set_forward_delay(struct net_bridge *br, unsigned long x);
extern int br_set_hello_time(struct net_bridge *br, unsigned long x);
extern int br_set_max_age(struct net_bridge *br, unsigned long x);

29
net/bridge/br_stp.c
View File

@ -544,18 +544,27 @@ int br_set_max_age(struct net_bridge *br, unsigned long val)
}
int br_set_forward_delay(struct net_bridge *br, unsigned long val)
void __br_set_forward_delay(struct net_bridge *br, unsigned long t)
{
unsigned long t = clock_t_to_jiffies(val);
if (br->stp_enabled != BR_NO_STP &&
(t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
return -ERANGE;
spin_lock_bh(&br->lock);
br->bridge_forward_delay = t;
if (br_is_root_bridge(br))
br->forward_delay = br->bridge_forward_delay;
spin_unlock_bh(&br->lock);
return 0;
}
int br_set_forward_delay(struct net_bridge *br, unsigned long val)
{
unsigned long t = clock_t_to_jiffies(val);
int err = -ERANGE;
spin_lock_bh(&br->lock);
if (br->stp_enabled != BR_NO_STP &&
(t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY))
goto unlock;
__br_set_forward_delay(br, t);
err = 0;
unlock:
spin_unlock_bh(&br->lock);
return err;
}

12
net/bridge/br_stp_if.c
View File

@ -129,6 +129,14 @@ static void br_stp_start(struct net_bridge *br)
char *envp[] = { NULL };
r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);
spin_lock_bh(&br->lock);
if (br->bridge_forward_delay < BR_MIN_FORWARD_DELAY)
__br_set_forward_delay(br, BR_MIN_FORWARD_DELAY);
else if (br->bridge_forward_delay < BR_MAX_FORWARD_DELAY)
__br_set_forward_delay(br, BR_MAX_FORWARD_DELAY);
if (r == 0) {
br->stp_enabled = BR_USER_STP;
br_debug(br, "userspace STP started\n");
@ -137,10 +145,10 @@ static void br_stp_start(struct net_bridge *br)
br_debug(br, "using kernel STP\n");
/* To start timers on any ports left in blocking */
spin_lock_bh(&br->lock);
br_port_state_selection(br);
spin_unlock_bh(&br->lock);
}
spin_unlock_bh(&br->lock);
}
static void br_stp_stop(struct net_bridge *br)