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author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 13:26:02 +0300 |
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committer | Jan Kara <jack@suse.cz> | 2017-10-31 17:54:56 +0100 |
commit | ab97f87325e28b7ef7717e6cb62e8da14a7176e1 (patch) | |
tree | 7ce8f0a747efaff1907f3774479dcbc2f4762c48 /kernel/audit_tree.c | |
parent | 6685df31255493c3f0e9e0b8bf885e4c9762fc5d (diff) | |
download | op-kernel-dev-ab97f87325e28b7ef7717e6cb62e8da14a7176e1.zip op-kernel-dev-ab97f87325e28b7ef7717e6cb62e8da14a7176e1.tar.gz |
fsnotify: convert fsnotify_mark.refcnt from atomic_t to refcount_t
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 fsnotify_mark.refcnt 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: Jan Kara <jack@suse.cz>
Diffstat (limited to 'kernel/audit_tree.c')
-rw-r--r-- | kernel/audit_tree.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index 011d46e..45ec960 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -1007,7 +1007,7 @@ static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify * We are guaranteed to have at least one reference to the mark from * either the inode or the caller of fsnotify_destroy_mark(). */ - BUG_ON(atomic_read(&entry->refcnt) < 1); + BUG_ON(refcount_read(&entry->refcnt) < 1); } static const struct fsnotify_ops audit_tree_ops = { |