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0896cade12
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable nfs_cache_defer_req.count is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
31 lines
1,018 B
C
31 lines
1,018 B
C
/*
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* Helper routines for the NFS client caches
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*
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* Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
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*/
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#include <linux/completion.h>
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#include <linux/sunrpc/cache.h>
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#include <linux/atomic.h>
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/*
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* Deferred request handling
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*/
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struct nfs_cache_defer_req {
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struct cache_req req;
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struct cache_deferred_req deferred_req;
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struct completion completion;
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refcount_t count;
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};
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extern int nfs_cache_upcall(struct cache_detail *cd, char *entry_name);
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extern struct nfs_cache_defer_req *nfs_cache_defer_req_alloc(void);
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extern void nfs_cache_defer_req_put(struct nfs_cache_defer_req *dreq);
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extern int nfs_cache_wait_for_upcall(struct nfs_cache_defer_req *dreq);
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extern int nfs_cache_register_net(struct net *net, struct cache_detail *cd);
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extern void nfs_cache_unregister_net(struct net *net, struct cache_detail *cd);
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extern int nfs_cache_register_sb(struct super_block *sb,
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struct cache_detail *cd);
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extern void nfs_cache_unregister_sb(struct super_block *sb,
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struct cache_detail *cd);
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