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authorEric Biggers <ebiggers@google.com>2019-10-06 14:24:27 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-01-27 14:46:49 +0100
commita8cfe559cb47108cc97353b65d79115cf6bf1b57 (patch)
tree8c52b613afd5f733ed5f4672c2ce43e454896209 /net
parente39340636dd980978224755f7bb641eeb08b88f4 (diff)
llc: fix sk_buff refcounting in llc_conn_state_process()
[ Upstream commit 36453c852816f19947ca482a595dffdd2efa4965 ] If llc_conn_state_process() sees that llc_conn_service() put the skb on a list, it will drop one fewer references to it. This is wrong because the current behavior is that llc_conn_service() never consumes a reference to the skb. The code also makes the number of skb references being dropped conditional on which of ind_prim and cfm_prim are nonzero, yet neither of these affects how many references are *acquired*. So there is extra code that tries to fix this up by sometimes taking another reference. Remove the unnecessary/broken refcounting logic and instead just add an skb_get() before the only two places where an extra reference is actually consumed. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/llc/llc_conn.c33
1 files changed, 6 insertions, 27 deletions
diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c
index 7340f23e16de..7fbc682aff04 100644
--- a/net/llc/llc_conn.c
+++ b/net/llc/llc_conn.c
@@ -64,12 +64,6 @@ int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
struct llc_sock *llc = llc_sk(skb->sk);
struct llc_conn_state_ev *ev = llc_conn_ev(skb);
- /*
- * We have to hold the skb, because llc_conn_service will kfree it in
- * the sending path and we need to look at the skb->cb, where we encode
- * llc_conn_state_ev.
- */
- skb_get(skb);
ev->ind_prim = ev->cfm_prim = 0;
/*
* Send event to state machine
@@ -77,21 +71,12 @@ int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
rc = llc_conn_service(skb->sk, skb);
if (unlikely(rc != 0)) {
printk(KERN_ERR "%s: llc_conn_service failed\n", __func__);
- goto out_kfree_skb;
- }
-
- if (unlikely(!ev->ind_prim && !ev->cfm_prim)) {
- /* indicate or confirm not required */
- if (!skb->next)
- goto out_kfree_skb;
goto out_skb_put;
}
- if (unlikely(ev->ind_prim && ev->cfm_prim)) /* Paranoia */
- skb_get(skb);
-
switch (ev->ind_prim) {
case LLC_DATA_PRIM:
+ skb_get(skb);
llc_save_primitive(sk, skb, LLC_DATA_PRIM);
if (unlikely(sock_queue_rcv_skb(sk, skb))) {
/*
@@ -108,6 +93,7 @@ int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
* skb->sk pointing to the newly created struct sock in
* llc_conn_handler. -acme
*/
+ skb_get(skb);
skb_queue_tail(&sk->sk_receive_queue, skb);
sk->sk_state_change(sk);
break;
@@ -123,7 +109,6 @@ int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
sk->sk_state_change(sk);
}
}
- kfree_skb(skb);
sock_put(sk);
break;
case LLC_RESET_PRIM:
@@ -132,14 +117,11 @@ int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
* RESET is not being notified to upper layers for now
*/
printk(KERN_INFO "%s: received a reset ind!\n", __func__);
- kfree_skb(skb);
break;
default:
- if (ev->ind_prim) {
+ if (ev->ind_prim)
printk(KERN_INFO "%s: received unknown %d prim!\n",
__func__, ev->ind_prim);
- kfree_skb(skb);
- }
/* No indication */
break;
}
@@ -181,15 +163,12 @@ int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
printk(KERN_INFO "%s: received a reset conf!\n", __func__);
break;
default:
- if (ev->cfm_prim) {
+ if (ev->cfm_prim)
printk(KERN_INFO "%s: received unknown %d prim!\n",
__func__, ev->cfm_prim);
- break;
- }
- goto out_skb_put; /* No confirmation */
+ /* No confirmation */
+ break;
}
-out_kfree_skb:
- kfree_skb(skb);
out_skb_put:
kfree_skb(skb);
return rc;