Re: [PATCH] Fix infinite loop on dev_mc_unsync()

[Luis R. Rodriguez]

On Fri, Nov 09, 2007 at 11:07:16AM -0800, Joe Perches wrote:
> On Fri, 2007-11-09 at 13:51 -0500, Luis R. Rodriguez wrote:
> > While reviewing net/core/dev_mcast.c I found what I think is an 
> > infinite loop on dev_mc_unsync(). This fixes it. We make use of
> > this guy on mac80211 in ieee80211_stop(). This is untested.
> > 
> > Signed-off-by: Luis R. Rodriguez <[EMAIL PROTECTED]>
> > 
> > diff --git a/net/core/dev_mcast.c b/net/core/dev_mcast.c
> > index 15241cf..5373c03 100644
> > --- a/net/core/dev_mcast.c
> > +++ b/net/core/dev_mcast.c
> > @@ -168,8 +168,10 @@ void dev_mc_unsync(struct net_device *to, struct 
> > net_device *from)
> >     da = from->mc_list;
> >     while (da != NULL) {
> >             next = da->next;
> > -           if (!da->da_synced)
> > +           if (!da->da_synced) {
> > +                   da = next;
> >                     continue;
> > +           }
> >             __dev_addr_delete(&to->mc_list, &to->mc_count,
> >                               da->da_addr, da->da_addrlen, 0);
> >             da->da_synced = 0;
> > -
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> 
> Perhaps this is clearer as:
> 
> void dev_mc_unsync(struct net_device *to, struct net_device *from)
> {
>       struct dev_addr_list *da;
> 
>       netif_tx_lock_bh(from);
>       netif_tx_lock_bh(to);
> 
>       da = from->mc_list;
>       while (da) {
>               if (da->da_synced) {
>                       __dev_addr_delete(&to->mc_list, &to->mc_count,
>                                         da->da_addr, da->da_addrlen, 0);
>                       __dev_addr_delete(&from->mc_list, &from->mc_count,
>                                         da->da_addr, da->da_addrlen, 0);
>                       da->da_synced = 0;
>               }
>               da = da->next;
>       }
> 
>       __dev_set_rx_mode(to);
> 
>       netif_tx_unlock_bh(to);
>       netif_tx_unlock_bh(from);
> }
> EXPORT_SYMBOL(dev_mc_unsync);

Sure, or better with a for loop and do away with next pointer then:

void dev_mc_unsync(struct net_device *to, struct net_device *from)
{
        struct dev_addr_list *da;

        netif_tx_lock_bh(from);
        netif_tx_lock_bh(to);

        for (da = from->mc_list; da; da = da->next) {
                if (!da->da_synced)
                        continue;
                __dev_addr_delete(&to->mc_list, &to->mc_count,
                                  da->da_addr, da->da_addrlen, 0);
                da->da_synced = 0;
                __dev_addr_delete(&from->mc_list, &from->mc_count,
                                  da->da_addr, da->da_addrlen, 0);
        }
        __dev_set_rx_mode(to);

        netif_tx_unlock_bh(to);
        netif_tx_unlock_bh(from);
}
EXPORT_SYMBOL(dev_mc_unsync);

Patch below.

Signed-off-by: Luis R. Rodriguez <[EMAIL PROTECTED]>

diff --git a/net/core/dev_mcast.c b/net/core/dev_mcast.c
index 15241cf..2aea8e1 100644
--- a/net/core/dev_mcast.c
+++ b/net/core/dev_mcast.c
@@ -160,14 +160,12 @@ EXPORT_SYMBOL(dev_mc_sync);
  */
 void dev_mc_unsync(struct net_device *to, struct net_device *from)
 {
-       struct dev_addr_list *da, *next;
+       struct dev_addr_list *da;
 
        netif_tx_lock_bh(from);
        netif_tx_lock_bh(to);
 
-       da = from->mc_list;
-       while (da != NULL) {
-               next = da->next;
+       for (da = from->mc_list; da; da = da->next) {
                if (!da->da_synced)
                        continue;
                __dev_addr_delete(&to->mc_list, &to->mc_count,
@@ -175,7 +173,6 @@ void dev_mc_unsync(struct net_device *to, struct net_device 
*from)
                da->da_synced = 0;
                __dev_addr_delete(&from->mc_list, &from->mc_count,
                                  da->da_addr, da->da_addrlen, 0);
-               da = next;
        }
        __dev_set_rx_mode(to);
 
-
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