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btrfs: convert btrfs_bio.refs 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>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Elena Reshetova 2017-03-03 10:55:10 +02:00 committed by David Sterba
parent f95fda8751
commit 140475ae4a
2 changed files with 5 additions and 5 deletions
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8
fs/btrfs/volumes.c
View File

@ -5301,22 +5301,22 @@ static struct btrfs_bio *alloc_btrfs_bio(int total_stripes, int real_stripes)
GFP_NOFS|__GFP_NOFAIL);
atomic_set(&bbio->error, 0);
atomic_set(&bbio->refs, 1);
refcount_set(&bbio->refs, 1);
return bbio;
}
void btrfs_get_bbio(struct btrfs_bio *bbio)
{
WARN_ON(!atomic_read(&bbio->refs));
atomic_inc(&bbio->refs);
WARN_ON(!refcount_read(&bbio->refs));
refcount_inc(&bbio->refs);
}
void btrfs_put_bbio(struct btrfs_bio *bbio)
{
if (!bbio)
return;
if (atomic_dec_and_test(&bbio->refs))
if (refcount_dec_and_test(&bbio->refs))
kfree(bbio);
}

2
fs/btrfs/volumes.h
View File

@ -298,7 +298,7 @@ struct btrfs_bio;
typedef void (btrfs_bio_end_io_t) (struct btrfs_bio *bio, int err);
struct btrfs_bio {
atomic_t refs;
refcount_t refs;
atomic_t stripes_pending;
struct btrfs_fs_info *fs_info;
u64 map_type; /* get from map_lookup->type */