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| author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 10:47:48 +0300 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2017-10-26 09:36:38 +0300 |
| commit | 0462d9921e3dfcb022600e4db2d67e6ceab57769 (patch) | |
| tree | c0574b57bb643f0f21145e1fb9113aeadf6f1b73 /drivers/s390/char/vmur.h | |
| parent | 3593eb944c65c7a0adfd679949e67f96d97d1768 (diff) | |
| download | linux-0462d9921e3dfcb022600e4db2d67e6ceab57769.tar.xz | |
vmur: convert urdev.ref_count 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 urdev.ref_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: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390/char/vmur.h')
| -rw-r--r-- | drivers/s390/char/vmur.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/s390/char/vmur.h b/drivers/s390/char/vmur.h index fa320ad4593d..35ea9d11d121 100644 --- a/drivers/s390/char/vmur.h +++ b/drivers/s390/char/vmur.h @@ -11,6 +11,8 @@ #ifndef _VMUR_H_ #define _VMUR_H_ +#include <linux/refcount.h> + #define DEV_CLASS_UR_I 0x20 /* diag210 unit record input device class */ #define DEV_CLASS_UR_O 0x10 /* diag210 unit record output device class */ /* @@ -69,7 +71,7 @@ struct urdev { size_t reclen; /* Record length for *write* CCWs */ int class; /* VM device class */ int io_request_rc; /* return code from I/O request */ - atomic_t ref_count; /* reference counter */ + refcount_t ref_count; /* reference counter */ wait_queue_head_t wait; /* wait queue to serialize open */ int open_flag; /* "urdev is open" flag */ spinlock_t open_lock; /* serialize critical sections */ |