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    Subject[PATCH 06/36] net, atm: convert atm_dev.refcnt from atomic_t to refcount_t
    Date
    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@intel.com>
    Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
    Signed-off-by: Kees Cook <keescook@chromium.org>
    Signed-off-by: David Windsor <dwindsor@gmail.com>
    ---
    include/linux/atmdev.h | 7 ++++---
    net/atm/proc.c | 2 +-
    net/atm/resources.c | 2 +-
    3 files changed, 6 insertions(+), 5 deletions(-)

    diff --git a/include/linux/atmdev.h b/include/linux/atmdev.h
    index 4d97a89..0ec9bdb 100644
    --- a/include/linux/atmdev.h
    +++ b/include/linux/atmdev.h
    @@ -11,6 +11,7 @@
    #include <linux/uio.h>
    #include <net/sock.h>
    #include <linux/atomic.h>
    +#include <linux/refcount.h>
    #include <uapi/linux/atmdev.h>

    #ifdef CONFIG_PROC_FS
    @@ -158,7 +159,7 @@ struct atm_dev {
    struct k_atm_dev_stats stats; /* statistics */
    char signal; /* signal status (ATM_PHY_SIG_*) */
    int link_rate; /* link rate (default: OC3) */
    - atomic_t refcnt; /* reference count */
    + refcount_t refcnt; /* reference count */
    spinlock_t lock; /* protect internal members */
    #ifdef CONFIG_PROC_FS
    struct proc_dir_entry *proc_entry; /* proc entry */
    @@ -261,13 +262,13 @@ static inline int atm_may_send(struct atm_vcc *vcc,unsigned int size)

    static inline void atm_dev_hold(struct atm_dev *dev)
    {
    - atomic_inc(&dev->refcnt);
    + refcount_inc(&dev->refcnt);
    }


    static inline void atm_dev_put(struct atm_dev *dev)
    {
    - if (atomic_dec_and_test(&dev->refcnt)) {
    + if (refcount_dec_and_test(&dev->refcnt)) {
    BUG_ON(!test_bit(ATM_DF_REMOVED, &dev->flags));
    if (dev->ops->dev_close)
    dev->ops->dev_close(dev);
    diff --git a/net/atm/proc.c b/net/atm/proc.c
    index 27c9c01..4caca2a 100644
    --- a/net/atm/proc.c
    +++ b/net/atm/proc.c
    @@ -61,7 +61,7 @@ static void atm_dev_info(struct seq_file *seq, const struct atm_dev *dev)
    add_stats(seq, "0", &dev->stats.aal0);
    seq_puts(seq, " ");
    add_stats(seq, "5", &dev->stats.aal5);
    - seq_printf(seq, "\t[%d]", atomic_read(&dev->refcnt));
    + seq_printf(seq, "\t[%d]", refcount_read(&dev->refcnt));
    seq_putc(seq, '\n');
    }

    diff --git a/net/atm/resources.c b/net/atm/resources.c
    index 0447d5d..9182447 100644
    --- a/net/atm/resources.c
    +++ b/net/atm/resources.c
    @@ -109,7 +109,7 @@ struct atm_dev *atm_dev_register(const char *type, struct device *parent,
    else
    memset(&dev->flags, 0, sizeof(dev->flags));
    memset(&dev->stats, 0, sizeof(dev->stats));
    - atomic_set(&dev->refcnt, 1);
    + refcount_set(&dev->refcnt, 1);

    if (atm_proc_dev_register(dev) < 0) {
    pr_err("atm_proc_dev_register failed for dev %s\n", type);
    --
    2.7.4
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