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Commit efc0c21c authored by Elena Reshetova's avatar Elena Reshetova Committed by Martin Schwidefsky
Browse files

s390: convert debug_info.ref_count 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: default avatarElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: default avatarHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDavid Windsor <dwindsor@gmail.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent d04a4c76

arch/s390/include/asm/debug.h

+2 −1
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/spinlock.h>

#include <linux/kernel.h>

#include <linux/time.h>

#include <linux/refcount.h>

#include <uapi/asm/debug.h>



#define DEBUG_MAX_LEVEL            6  /* debug levels range from 0 to 6 */
@@ -31,7 +32,7 @@ struct debug_view; 
typedef struct debug_info {	

	struct debug_info* next;

	struct debug_info* prev;

	atomic_t ref_count;

	refcount_t ref_count;

	spinlock_t lock;			

	int level;

	int nr_areas;

arch/s390/kernel/debug.c

+4 −4
Original line number Diff line number Diff line
@@ -277,7 +277,7 @@ debug_info_alloc(const char *name, int pages_per_area, int nr_areas, 
	memset(rc->views, 0, DEBUG_MAX_VIEWS * sizeof(struct debug_view *));

	memset(rc->debugfs_entries, 0 ,DEBUG_MAX_VIEWS *

		sizeof(struct dentry*));

	atomic_set(&(rc->ref_count), 0);

	refcount_set(&(rc->ref_count), 0);



	return rc;
@@ -361,7 +361,7 @@ debug_info_create(const char *name, int pages_per_area, int nr_areas, 
        debug_area_last = rc;

        rc->next = NULL;



	debug_info_get(rc);

	refcount_set(&rc->ref_count, 1);

out:

	return rc;

}
@@ -416,7 +416,7 @@ static void 
debug_info_get(debug_info_t * db_info)

{

	if (db_info)

		atomic_inc(&db_info->ref_count);

		refcount_inc(&db_info->ref_count);

}



/*
@@ -431,7 +431,7 @@ debug_info_put(debug_info_t *db_info) 


	if (!db_info)

		return;

	if (atomic_dec_and_test(&db_info->ref_count)) {

	if (refcount_dec_and_test(&db_info->ref_count)) {

		for (i = 0; i < DEBUG_MAX_VIEWS; i++) {

			if (!db_info->views[i])

				continue;