From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120205220952.526747546@pcw.home.local> Date: Sun, 05 Feb 2012 23:11:01 +0100 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "J. Bruce Fields" , Greg KH Subject: [PATCH 72/91] svcrpc: fix double-free on shutdown of nfsd after changing pool mode In-Reply-To: <0635750f5f06ed2ca212b91fcb5c4483@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: 2.6.27-longterm review patch. If anyone has any objections, please let us know. ------------------ commit 61c8504c428edcebf23b97775a129c5b393a302b upstream. The pool_to and to_pool fields of the global svc_pool_map are freed on shutdown, but are initialized in nfsd startup only in the SVC_POOL_PERCPU and SVC_POOL_PERNODE cases. They *are* initialized to zero on kernel startup. So as long as you use only SVC_POOL_GLOBAL (the default), this will never be a problem. You're also OK if you only ever use SVC_POOL_PERCPU or SVC_POOL_PERNODE. However, the following sequence events leads to a double-free: 1. set SVC_POOL_PERCPU or SVC_POOL_PERNODE 2. start nfsd: both fields are initialized. 3. shutdown nfsd: both fields are freed. 4. set SVC_POOL_GLOBAL 5. start nfsd: the fields are left untouched. 6. shutdown nfsd: now we try to free them again. Step 4 is actually unnecessary, since (for some bizarre reason), nfsd automatically resets the pool mode to SVC_POOL_GLOBAL on shutdown. Signed-off-by: J. Bruce Fields Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/svc.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) Index: longterm-2.6.27/net/sunrpc/svc.c =================================================================== --- longterm-2.6.27.orig/net/sunrpc/svc.c 2012-02-05 22:34:32.810915144 +0100 +++ longterm-2.6.27/net/sunrpc/svc.c 2012-02-05 22:34:45.104915090 +0100 @@ -163,6 +163,7 @@ fail_free: kfree(m->to_pool); + m->to_pool = NULL; fail: return -ENOMEM; } @@ -283,7 +284,9 @@ if (!--m->count) { m->mode = SVC_POOL_DEFAULT; kfree(m->to_pool); + m->to_pool = NULL; kfree(m->pool_to); + m->pool_to = NULL; m->npools = 0; }