[PATCH 15/15] kernel: convert kcov.refcount from atomic_t to refcount_t
From: Elena Reshetova <elena.reshetova@intel.com>
Date: 2017-07-17 10:46:54
Also in:
linux-fsdevel, lkml
Subsystem:
kcov, the rest · Maintainer:
Linus Torvalds
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. Suggested-by: Kees Cook <redacted> Reviewed-by: David Windsor <redacted> Reviewed-by: Hans Liljestrand <redacted> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> --- kernel/kcov.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/kernel/kcov.c b/kernel/kcov.c
index cd77199..a6c7df3 100644
--- a/kernel/kcov.c
+++ b/kernel/kcov.c@@ -19,6 +19,7 @@ #include <linux/debugfs.h> #include <linux/uaccess.h> #include <linux/kcov.h> +#include <linux/refcount.h> #include <asm/setup.h> /*
@@ -35,7 +36,7 @@ struct kcov { * - opened file descriptor * - task with enabled coverage (we can't unwire it from another task) */ - atomic_t refcount; + refcount_t refcount; /* The lock protects mode, size, area and t. */ spinlock_t lock; enum kcov_mode mode;
@@ -94,12 +95,12 @@ EXPORT_SYMBOL(__sanitizer_cov_trace_pc); static void kcov_get(struct kcov *kcov) { - atomic_inc(&kcov->refcount); + refcount_inc(&kcov->refcount); } static void kcov_put(struct kcov *kcov) { - if (atomic_dec_and_test(&kcov->refcount)) { + if (refcount_dec_and_test(&kcov->refcount)) { vfree(kcov->area); kfree(kcov); }
@@ -175,7 +176,7 @@ static int kcov_open(struct inode *inode, struct file *filep) kcov = kzalloc(sizeof(*kcov), GFP_KERNEL); if (!kcov) return -ENOMEM; - atomic_set(&kcov->refcount, 1); + refcount_set(&kcov->refcount, 1); spin_lock_init(&kcov->lock); filep->private_data = kcov; return nonseekable_open(inode, filep);
--
2.7.4