Re: [PATCH 15/19] kernel: convert audit_tree.count from atomic_t to refcount_t

refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova <elena.reshetova(a)intel.com&gt; Signed-off-by: Hans Liljestrand <ishkamiel(a)gmail.com&gt; Signed-off-by: Kees Cook <keescook(a)chromium.org&gt; Signed-off-by: David Windsor <dwindsor(a)gmail.com&gt; --- kernel/audit_tree.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index 7b44195..7ed617b 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -9,7 +9,7 @@ struct audit_tree; struct audit_chunk; struct audit_tree { - atomic_t count; + refcount_t count; int goner; struct audit_chunk *root; struct list_head chunks; @@ -77,7 +77,7 @@ static struct audit_tree *alloc_tree(const char *s) tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL); if (tree) { - atomic_set(&tree->count, 1); + refcount_set(&tree->count, 1); tree->goner = 0; INIT_LIST_HEAD(&tree->chunks); INIT_LIST_HEAD(&tree->rules); @@ -91,12 +91,12 @@ static struct audit_tree *alloc_tree(const char *s) static inline void get_tree(struct audit_tree *tree) { - atomic_inc(&tree->count); + refcount_inc(&tree->count); } static inline void put_tree(struct audit_tree *tree) { - if (atomic_dec_and_test(&tree->count)) + if (refcount_dec_and_test(&tree->count)) kfree_rcu(tree, head); }