Commit eba6dd69 authored by Elena Reshetova's avatar Elena Reshetova Committed by Anna Schumaker
Browse files

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: 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 avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent a2a5dea7

fs/nfs/pnfs.c

+6 −6
Original line number Diff line number Diff line
@@ -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;

}

fs/nfs/pnfs.h

+2 −2
Original line number Diff line number Diff line
@@ -64,7 +64,7 @@ struct pnfs_layout_segment { 
	struct list_head pls_list;

	struct list_head pls_lc_list;

	struct pnfs_layout_range pls_range;

	atomic_t pls_refcount;

	refcount_t pls_refcount;

	u32 pls_seq;

	unsigned long pls_flags;

	struct pnfs_layout_hdr *pls_layout;
@@ -394,7 +394,7 @@ static inline struct pnfs_layout_segment * 
pnfs_get_lseg(struct pnfs_layout_segment *lseg)

{

	if (lseg) {

		atomic_inc(&lseg->pls_refcount);

		refcount_inc(&lseg->pls_refcount);

		smp_mb__after_atomic();

	}

	return lseg;

CRA Git | Maintained and supported by SUSTech CRA and CCSE