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[PATCH 8/9] tools: convert thread.refcnt from atomic_t to refcount_t

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  [PATCH 8/9] tools: convert thread.refcnt from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-02-21 16:40 +0100
    Re: [PATCH 8/9] tools: convert thread.refcnt from atomic_t to  refcount_t Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-02-23 00:20 +0100

#1585420 — [PATCH 8/9] tools: convert thread.refcnt 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@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>
---
 tools/perf/util/thread.c | 6 +++---
 tools/perf/util/thread.h | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index f5af87f..74e79d2 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -53,7 +53,7 @@ struct thread *thread__new(pid_t pid, pid_t tid)
 			goto err_thread;
 
 		list_add(&comm->list, &thread->comm_list);
-		atomic_set(&thread->refcnt, 1);
+		refcount_set(&thread->refcnt, 1);
 		RB_CLEAR_NODE(&thread->rb_node);
 	}
 
@@ -88,13 +88,13 @@ void thread__delete(struct thread *thread)
 struct thread *thread__get(struct thread *thread)
 {
 	if (thread)
-		atomic_inc(&thread->refcnt);
+		refcount_inc(&thread->refcnt);
 	return thread;
 }
 
 void thread__put(struct thread *thread)
 {
-	if (thread && atomic_dec_and_test(&thread->refcnt)) {
+	if (thread && refcount_dec_and_test(&thread->refcnt)) {
 		/*
 		 * Remove it from the dead_threads list, as last reference
 		 * is gone.
diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
index 99263cb..e571885 100644
--- a/tools/perf/util/thread.h
+++ b/tools/perf/util/thread.h
@@ -1,7 +1,7 @@
 #ifndef __PERF_THREAD_H
 #define __PERF_THREAD_H
 
-#include <linux/atomic.h>
+#include <linux/refcount.h>
 #include <linux/rbtree.h>
 #include <linux/list.h>
 #include <unistd.h>
@@ -23,7 +23,7 @@ struct thread {
 	pid_t			tid;
 	pid_t			ppid;
 	int			cpu;
-	atomic_t		refcnt;
+	refcount_t		refcnt;
 	char			shortname[3];
 	bool			comm_set;
 	int			comm_len;
-- 
2.7.4

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#1586541 — Re: [PATCH 8/9] tools: convert thread.refcnt from atomic_t to refcount_t

Em Tue, Feb 21, 2017 at 05:35:02PM +0200, Elena Reshetova escreveu:
> 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.

You forgot this one, fixing it...

@@ -1439,7 +1439,7 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
        if (machine->last_match == th)
                machine->last_match = NULL;
 
-       BUG_ON(atomic_read(&th->refcnt) == 0);
+       BUG_ON(refcount_read(&th->refcnt) == 0);
        if (lock)
                pthread_rwlock_wrlock(&machine->threads_lock);
        rb_erase_init(&th->rb_node, &machine->threads);
[acme@jouet linux]$
 
> 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>
> ---
>  tools/perf/util/thread.c | 6 +++---
>  tools/perf/util/thread.h | 4 ++--
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
> index f5af87f..74e79d2 100644
> --- a/tools/perf/util/thread.c
> +++ b/tools/perf/util/thread.c
> @@ -53,7 +53,7 @@ struct thread *thread__new(pid_t pid, pid_t tid)
>  			goto err_thread;
>  
>  		list_add(&comm->list, &thread->comm_list);
> -		atomic_set(&thread->refcnt, 1);
> +		refcount_set(&thread->refcnt, 1);
>  		RB_CLEAR_NODE(&thread->rb_node);
>  	}
>  
> @@ -88,13 +88,13 @@ void thread__delete(struct thread *thread)
>  struct thread *thread__get(struct thread *thread)
>  {
>  	if (thread)
> -		atomic_inc(&thread->refcnt);
> +		refcount_inc(&thread->refcnt);
>  	return thread;
>  }
>  
>  void thread__put(struct thread *thread)
>  {
> -	if (thread && atomic_dec_and_test(&thread->refcnt)) {
> +	if (thread && refcount_dec_and_test(&thread->refcnt)) {
>  		/*
>  		 * Remove it from the dead_threads list, as last reference
>  		 * is gone.
> diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
> index 99263cb..e571885 100644
> --- a/tools/perf/util/thread.h
> +++ b/tools/perf/util/thread.h
> @@ -1,7 +1,7 @@
>  #ifndef __PERF_THREAD_H
>  #define __PERF_THREAD_H
>  
> -#include <linux/atomic.h>
> +#include <linux/refcount.h>
>  #include <linux/rbtree.h>
>  #include <linux/list.h>
>  #include <unistd.h>
> @@ -23,7 +23,7 @@ struct thread {
>  	pid_t			tid;
>  	pid_t			ppid;
>  	int			cpu;
> -	atomic_t		refcnt;
> +	refcount_t		refcnt;
>  	char			shortname[3];
>  	bool			comm_set;
>  	int			comm_len;
> -- 
> 2.7.4

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