[PATCH 4.9 03/88] net: properly release sk_frag.page

From: Greg Kroah-Hartman
Date: Tue Mar 28 2017 - 09:11:52 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@xxxxxxxxxx>


[ Upstream commit 22a0e18eac7a9e986fec76c60fa4a2926d1291e2 ]

I mistakenly added the code to release sk->sk_frag in
sk_common_release() instead of sk_destruct()

TCP sockets using sk->sk_allocation == GFP_ATOMIC do no call
sk_common_release() at close time, thus leaking one (order-3) page.

iSCSI is using such sockets.

Fixes: 5640f7685831 ("net: use a per task frag allocator")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/sock.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1437,6 +1437,11 @@ static void __sk_destruct(struct rcu_hea
pr_debug("%s: optmem leakage (%d bytes) detected\n",
__func__, atomic_read(&sk->sk_omem_alloc));

+ if (sk->sk_frag.page) {
+ put_page(sk->sk_frag.page);
+ sk->sk_frag.page = NULL;
+ }
+
if (sk->sk_peer_cred)
put_cred(sk->sk_peer_cred);
put_pid(sk->sk_peer_pid);
@@ -2738,11 +2743,6 @@ void sk_common_release(struct sock *sk)

sk_refcnt_debug_release(sk);

- if (sk->sk_frag.page) {
- put_page(sk->sk_frag.page);
- sk->sk_frag.page = NULL;
- }
-
sock_put(sk);
}
EXPORT_SYMBOL(sk_common_release);