Re: [held lock freed] Re: [GIT] Networking
From: Arnd Bergmann
Date: Mon Mar 21 2011 - 10:50:26 EST
On Monday 21 March 2011, Eric Dumazet wrote:
> [PATCH] ipx: fix ipx_release()
>
> Commit b0d0d915d1d1a0 (remove the BKL) added a regression, because
> sock_put() can free memory while we are going to use it later.
>
> Fix is to delay sock_put() after release_sock().
>
> Reported-by: Ingo Molnar <mingo@xxxxxxx>
> Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
Your fix looks good, thanks Eric!
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
I believe I made the same mistake in atalk_release and x25_release:
8<------------
net: fix atalk_release and x25_release
The recent BKL removal has introduced a use-after-free problem
in multiple network protocols. This fixes the problem in appletalk
and x25 by ensuring that we call the final sock_put() after
releasing the socket lock.
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
index 3d4f4b0..206e771 100644
--- a/net/appletalk/ddp.c
+++ b/net/appletalk/ddp.c
@@ -1051,6 +1051,7 @@ static int atalk_release(struct socket *sock)
{
struct sock *sk = sock->sk;
+ sock_hold(sk);
lock_sock(sk);
if (sk) {
sock_orphan(sk);
@@ -1058,6 +1059,8 @@ static int atalk_release(struct socket *sock)
atalk_destroy_socket(sk);
}
release_sock(sk);
+ sock_put(sk);
+
return 0;
}
diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index 4680b1e..b2cf1db 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -669,8 +669,8 @@ static int x25_release(struct socket *sock)
sock_orphan(sk);
out:
- release_sock(sk);
sock_put(sk);
+ release_sock(sk);
return 0;
}
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