Messages in this thread Patch in this message | | | Date | Mon, 23 Jan 2012 15:39:30 -0800 | From | Greg KH <> | Subject | [44/90] svcrpc: fix double-free on shutdown of nfsd after changing pool mode |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: "J. Bruce Fields" <bfields@redhat.com>
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 <bfields@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- net/sunrpc/svc.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -167,6 +167,7 @@ svc_pool_map_alloc_arrays(struct svc_poo fail_free: kfree(m->to_pool); + m->to_pool = NULL; fail: return -ENOMEM; } @@ -287,7 +288,9 @@ svc_pool_map_put(void) 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; }
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