fs, nfs: convert pnfs_layout_segment.pls_refcount 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: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 3bcd669a3152..499bb710713e 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -450,7 +450,7 @@ pnfs_init_lseg(struct pnfs_layout_hdr *lo, struct pnfs_layout_segment *lseg,
 {
         INIT_LIST_HEAD(&lseg->pls_list);
         INIT_LIST_HEAD(&lseg->pls_lc_list);
-        atomic_set(&lseg->pls_refcount, 1);
+        refcount_set(&lseg->pls_refcount, 1);
         set_bit(NFS_LSEG_VALID, &lseg->pls_flags);
         lseg->pls_layout = lo;
         lseg->pls_range = *range;
@@ -507,13 +507,13 @@ pnfs_put_lseg(struct pnfs_layout_segment *lseg)
                 return;
 
         dprintk("%s: lseg %p ref %d valid %d\n", __func__, lseg,
-                atomic_read(&lseg->pls_refcount),
+                refcount_read(&lseg->pls_refcount),
                 test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
 
         lo = lseg->pls_layout;
         inode = lo->plh_inode;
 
-        if (atomic_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {
+        if (refcount_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {
                 if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags)) {
                         spin_unlock(&inode->i_lock);
                         return;
@@ -551,7 +551,7 @@ pnfs_lseg_range_contained(const struct pnfs_layout_range *l1,
 static bool pnfs_lseg_dec_and_remove_zero(struct pnfs_layout_segment *lseg,
                 struct list_head *tmp_list)
 {
-        if (!atomic_dec_and_test(&lseg->pls_refcount))
+        if (!refcount_dec_and_test(&lseg->pls_refcount))
                 return false;
         pnfs_layout_remove_lseg(lseg->pls_layout, lseg);
         list_add(&lseg->pls_list, tmp_list);
@@ -570,7 +570,7 @@ static int mark_lseg_invalid(struct pnfs_layout_segment *lseg,
                  * outstanding io is finished.
                  */
                 dprintk("%s: lseg %p ref %d\n", __func__, lseg,
-                        atomic_read(&lseg->pls_refcount));
+                        refcount_read(&lseg->pls_refcount));
                 if (pnfs_lseg_dec_and_remove_zero(lseg, tmp_list))
                         rv = 1;
         }
@@ -1546,7 +1546,7 @@ pnfs_find_lseg(struct pnfs_layout_hdr *lo,
         }
 
         dprintk("%s:Return lseg %p ref %d\n",
-                __func__, ret, ret ? atomic_read(&ret->pls_refcount) : 0);
+                __func__, ret, ret ? refcount_read(&ret->pls_refcount) : 0);
         return ret;
 }