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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>
This commit is contained in:
Elena Reshetova 2017-10-20 12:53:32 +03:00 committed by Anna Schumaker
parent a2a5dea7b6
commit eba6dd6917
2 changed files with 8 additions and 8 deletions
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12
fs/nfs/pnfs.c
View File

@ -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;
}

4
fs/nfs/pnfs.h
View File

@ -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;