ipsec: Fix deadlock in xfrm_state management.

Ever since commit 4c563f7669c10a12354b72b518c2287ffc6ebfb3
("[XFRM]: Speed up xfrm_policy and xfrm_state walking") it is
illegal to call __xfrm_state_destroy (and thus xfrm_state_put())
with xfrm_state_lock held.  If we do, we'll deadlock since we
have the lock already and __xfrm_state_destroy() tries to take
it again.

Fix this by pushing the xfrm_state_put() calls after the lock
is dropped.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 23 insertions, 9 deletions

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 4c6914ef7d92..7bd62f61593f 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -780,11 +780,13 @@ xfrm_state_find(xfrm_address_t *daddr, xfrm_address_t *saddr,
 {
         unsigned int h;
         struct hlist_node *entry;
-        struct xfrm_state *x, *x0;
+        struct xfrm_state *x, *x0, *to_put;
         int acquire_in_progress = 0;
         int error = 0;
         struct xfrm_state *best = NULL;
 
+        to_put = NULL;
+
         spin_lock_bh(&xfrm_state_lock);
         h = xfrm_dst_hash(daddr, saddr, tmpl->reqid, family);
         hlist_for_each_entry(x, entry, xfrm_state_bydst+h, bydst) {
@@ -833,7 +835,7 @@ xfrm_state_find(xfrm_address_t *daddr, xfrm_address_t *saddr,
                 if (tmpl->id.spi &&
                     (x0 = __xfrm_state_lookup(daddr, tmpl->id.spi,
                                               tmpl->id.proto, family)) != NULL) {
-                        xfrm_state_put(x0);
+                        to_put = x0;
                         error = -EEXIST;
                         goto out;
                 }
@@ -849,7 +851,7 @@ xfrm_state_find(xfrm_address_t *daddr, xfrm_address_t *saddr,
                 error = security_xfrm_state_alloc_acquire(x, pol->security, fl->secid);
                 if (error) {
                         x->km.state = XFRM_STATE_DEAD;
-                        xfrm_state_put(x);
+                        to_put = x;
                         x = NULL;
                         goto out;
                 }
@@ -870,7 +872,7 @@ xfrm_state_find(xfrm_address_t *daddr, xfrm_address_t *saddr,
                         xfrm_hash_grow_check(x->bydst.next != NULL);
                 } else {
                         x->km.state = XFRM_STATE_DEAD;
-                        xfrm_state_put(x);
+                        to_put = x;
                         x = NULL;
                         error = -ESRCH;
                 }
@@ -881,6 +883,8 @@ out:
         else
                 *err = acquire_in_progress ? -EAGAIN : error;
         spin_unlock_bh(&xfrm_state_lock);
+        if (to_put)
+                xfrm_state_put(to_put);
         return x;
 }
 
@@ -1067,18 +1071,20 @@ static struct xfrm_state *__xfrm_find_acq_byseq(u32 seq);
 
 int xfrm_state_add(struct xfrm_state *x)
 {
-        struct xfrm_state *x1;
+        struct xfrm_state *x1, *to_put;
         int family;
         int err;
         int use_spi = xfrm_id_proto_match(x->id.proto, IPSEC_PROTO_ANY);
 
         family = x->props.family;
 
+        to_put = NULL;
+
         spin_lock_bh(&xfrm_state_lock);
 
         x1 = __xfrm_state_locate(x, use_spi, family);
         if (x1) {
-                xfrm_state_put(x1);
+                to_put = x1;
                 x1 = NULL;
                 err = -EEXIST;
                 goto out;
@@ -1088,7 +1094,7 @@ int xfrm_state_add(struct xfrm_state *x)
                 x1 = __xfrm_find_acq_byseq(x->km.seq);
                 if (x1 && ((x1->id.proto != x->id.proto) ||
                     xfrm_addr_cmp(&x1->id.daddr, &x->id.daddr, family))) {
-                        xfrm_state_put(x1);
+                        to_put = x1;
                         x1 = NULL;
                 }
         }
@@ -1110,6 +1116,9 @@ out:
                 xfrm_state_put(x1);
         }
 
+        if (to_put)
+                xfrm_state_put(to_put);
+
         return err;
 }
 EXPORT_SYMBOL(xfrm_state_add);
@@ -1269,10 +1278,12 @@ EXPORT_SYMBOL(xfrm_state_migrate);
 
 int xfrm_state_update(struct xfrm_state *x)
 {
-        struct xfrm_state *x1;
+        struct xfrm_state *x1, *to_put;
         int err;
         int use_spi = xfrm_id_proto_match(x->id.proto, IPSEC_PROTO_ANY);
 
+        to_put = NULL;
+
         spin_lock_bh(&xfrm_state_lock);
         x1 = __xfrm_state_locate(x, use_spi, x->props.family);
 
@@ -1281,7 +1292,7 @@ int xfrm_state_update(struct xfrm_state *x)
                 goto out;
 
         if (xfrm_state_kern(x1)) {
-                xfrm_state_put(x1);
+                to_put = x1;
                 err = -EEXIST;
                 goto out;
         }
@@ -1295,6 +1306,9 @@ int xfrm_state_update(struct xfrm_state *x)
 out:
         spin_unlock_bh(&xfrm_state_lock);
 
+        if (to_put)
+                xfrm_state_put(to_put);
+
         if (err)
                 return err;