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net: ipv4: remove erroneous advancement of list pointer

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Causes crash when lifetime expires on an adress as garbage is
dereferenced soon after.

This used to look like this:

 for (ifap = &ifa->ifa_dev->ifa_list;
      *ifap != NULL; ifap = &(*ifap)->ifa_next) {
          if (*ifap == ifa) ...

but this was changed to:

struct in_ifaddr *tmp;

ifap = &ifa->ifa_dev->ifa_list;
tmp = rtnl_dereference(*ifap);
while (tmp) {
   tmp = rtnl_dereference(tmp->ifa_next); // Bogus
   if (rtnl_dereference(*ifap) == ifa) {
     ...
   ifap = &tmp->ifa_next;		// Can be NULL
   tmp = rtnl_dereference(*ifap);	// Dereference
   }
}

Remove the bogus assigment/list entry skip.

Fixes: 2638eb8b50 ("net: ipv4: provide __rcu annotation for ifa_list")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal 2019-06-17 16:02:27 +02:00 committed by David S. Miller
parent 78fe8a28fb
commit 40008e9211
1 changed files with 1 additions and 2 deletions
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3
net/ipv4/devinet.c
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@ -745,8 +745,7 @@ static void check_lifetime(struct work_struct *work)
ifap = &ifa->ifa_dev->ifa_list;
tmp = rtnl_dereference(*ifap);
while (tmp) {
tmp = rtnl_dereference(tmp->ifa_next);
if (rtnl_dereference(*ifap) == ifa) {
if (tmp == ifa) {
inet_del_ifa(ifa->ifa_dev,
ifap, 1);
break;