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| author | J. Bruce Fields <bfields@redhat.com> | 2011-12-22 18:22:49 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2012-01-25 16:13:31 -0800 |
| commit | bcf641763cf916797543f032714e0478e48c2ef7 (patch) | |
| tree | 224d3365303c33847f54c454ca0111c887c413d1 /net | |
| parent | b20b30d4d382e151daaee5466ce2427f653170af (diff) | |
| download | lwn-bcf641763cf916797543f032714e0478e48c2ef7.tar.gz lwn-bcf641763cf916797543f032714e0478e48c2ef7.zip | |
svcrpc: fix double-free on shutdown of nfsd after changing pool mode
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>
Diffstat (limited to 'net')
| -rw-r--r-- | net/sunrpc/svc.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 6e038884ae0c..5443ffdf336c 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -167,6 +167,7 @@ svc_pool_map_alloc_arrays(struct svc_pool_map *m, unsigned int maxpools) 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; } |