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Message-Id: <1485262100-12366-1-git-send-email-dwindsor@gmail.com>
Date: Tue, 24 Jan 2017 07:48:20 -0500
From: David Windsor <dwindsor@...il.com>
To: netdev@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Cc: keescook@...omium.org,
elena.reshetova@...el.com,
ja@....bg,
dwindsor@...il.com,
ishkamiel@...il.com
Subject: [PATCH net] net: free ip_vs_dest structs when refcnt=0
Currently, the ip_vs_dest cache frees ip_vs_dest objects when their reference
count becomes < 0. Aside from not being semantically sound, this is problematic
for the new type refcount_t, which will be introduced shortly in a separate patch.
refcount_t is the new kernel type for holding reference counts, and provides
overflow protection and a constrained interface relative to atomic_t (the type
currently being used for kernel reference counts).
Per Juilan Anastasov: "The problem is that dest_trash currently holds deleted
dests (unlinked from RCU lists) with refcnt=0." Changing dest_trash to hold
dest with refcnt=1 will allow us to free ip_vs_dest structs when their refcnt=0,
in ip_vs_dest_put_and_free().
Signed-off-by: David Windsor <dwindsor@...il.com>
---
include/net/ip_vs.h | 2 +-
net/netfilter/ipvs/ip_vs_ctl.c | 4 +---
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index cd6018a..a3e78ad 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -1421,7 +1421,7 @@ static inline void ip_vs_dest_put(struct ip_vs_dest *dest)
static inline void ip_vs_dest_put_and_free(struct ip_vs_dest *dest)
{
- if (atomic_dec_return(&dest->refcnt) < 0)
+ if (atomic_dec_and_test(&dest->refcnt))
kfree(dest);
}
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 55e0169..6b5492e 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -711,7 +711,6 @@ ip_vs_trash_get_dest(struct ip_vs_service *svc, int dest_af,
dest->vport == svc->port))) {
/* HIT */
list_del(&dest->t_list);
- ip_vs_dest_hold(dest);
goto out;
}
}
@@ -1084,7 +1083,6 @@ static void __ip_vs_del_dest(struct netns_ipvs *ipvs, struct ip_vs_dest *dest,
list_add(&dest->t_list, &ipvs->dest_trash);
dest->idle_start = 0;
spin_unlock_bh(&ipvs->dest_trash_lock);
- ip_vs_dest_put(dest);
}
@@ -1160,7 +1158,7 @@ static void ip_vs_dest_trash_expire(unsigned long data)
spin_lock(&ipvs->dest_trash_lock);
list_for_each_entry_safe(dest, next, &ipvs->dest_trash, t_list) {
- if (atomic_read(&dest->refcnt) > 0)
+ if (atomic_read(&dest->refcnt) > 1)
continue;
if (dest->idle_start) {
if (time_before(now, dest->idle_start +
--
2.7.4
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