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ref_tracker: implement use-after-free detection 

Whenever ref_tracker_dir_init() is called, mark the struct ref_tracker_dir
as dead.

Test the dead status from ref_tracker_alloc() and ref_tracker_free()

This should detect buggy dev_put()/dev_hold() happening too late
in netdevice dismantle process.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2022-02-04 14:42:35 -08:00 committed by David S. Miller
parent cc3063502e
commit e3ececfe66
2 changed files with 7 additions and 0 deletions
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2
include/linux/ref_tracker.h
View File

@ -13,6 +13,7 @@ struct ref_tracker_dir {
spinlock_t lock;
unsigned int quarantine_avail;
refcount_t untracked;
bool dead;
struct list_head list; /* List of active trackers */
struct list_head quarantine; /* List of dead trackers */
#endif
@ -26,6 +27,7 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
INIT_LIST_HEAD(&dir->quarantine);
spin_lock_init(&dir->lock);
dir->quarantine_avail = quarantine_count;
dir->dead = false;
refcount_set(&dir->untracked, 1);
stack_depot_init();
}

5
lib/ref_tracker.c
View File

@ -20,6 +20,7 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
unsigned long flags;
bool leak = false;
dir->dead = true;
spin_lock_irqsave(&dir->lock, flags);
list_for_each_entry_safe(tracker, n, &dir->quarantine, head) {
list_del(&tracker->head);
@ -72,6 +73,8 @@ int ref_tracker_alloc(struct ref_tracker_dir *dir,
gfp_t gfp_mask = gfp;
unsigned long flags;
WARN_ON_ONCE(dir->dead);
if (gfp & __GFP_DIRECT_RECLAIM)
gfp_mask |= __GFP_NOFAIL;
*trackerp = tracker = kzalloc(sizeof(*tracker), gfp_mask);
@ -100,6 +103,8 @@ int ref_tracker_free(struct ref_tracker_dir *dir,
unsigned int nr_entries;
unsigned long flags;
WARN_ON_ONCE(dir->dead);
if (!tracker) {
refcount_dec(&dir->untracked);
return -EEXIST;