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[XFS] Really fix use after free in xfs_iunpin.

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The previous attempts to fix the linux inode use-after-free in xfs_iunpin
simply made the problem harder to hit. We actually need complete exclusion
between xfs_reclaim and xfs_iunpin, as well as ensuring that the i_flags
are consistent during both of these functions. Introduce a new spinlock
for exclusion and the i_flags, and fix up xfs_iunpin to use igrab before
marking the inode dirty.

SGI-PV: 952967
SGI-Modid: xfs-linux-melb:xfs-kern:26964a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
This commit is contained in:
David Chinner 2006-09-28 11:06:03 +10:00 committed by Tim Shimmin
parent 01106eae97
commit f273ab848b
6 changed files with 35 additions and 3 deletions
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2
fs/xfs/linux-2.6/xfs_super.c
View file

@ -227,7 +227,9 @@ xfs_initialize_vnode(
xfs_revalidate_inode(XFS_BHVTOM(bdp), vp, ip);
xfs_set_inodeops(inode);
spin_lock(&ip->i_flags_lock);
ip->i_flags &= ~XFS_INEW;
spin_unlock(&ip->i_flags_lock);
barrier();
unlock_new_inode(inode);

6
fs/xfs/xfs_iget.c
View file

@ -243,7 +243,9 @@ again:
XFS_STATS_INC(xs_ig_found);
spin_lock(&ip->i_flags_lock);
ip->i_flags &= ~XFS_IRECLAIMABLE;
spin_unlock(&ip->i_flags_lock);
version = ih->ih_version;
read_unlock(&ih->ih_lock);
xfs_ihash_promote(ih, ip, version);
@ -297,7 +299,9 @@ finish_inode:
if (lock_flags != 0)
xfs_ilock(ip, lock_flags);
spin_lock(&ip->i_flags_lock);
ip->i_flags &= ~XFS_ISTALE;
spin_unlock(&ip->i_flags_lock);
vn_trace_exit(vp, "xfs_iget.found",
(inst_t *)__return_address);
@ -367,7 +371,9 @@ finish_inode:
ih->ih_next = ip;
ip->i_udquot = ip->i_gdquot = NULL;
ih->ih_version++;
spin_lock(&ip->i_flags_lock);
ip->i_flags |= XFS_INEW;
spin_unlock(&ip->i_flags_lock);
write_unlock(&ih->ih_lock);

21
fs/xfs/xfs_inode.c
View file

@ -867,6 +867,7 @@ xfs_iread(
ip = kmem_zone_zalloc(xfs_inode_zone, KM_SLEEP);
ip->i_ino = ino;
ip->i_mount = mp;
spin_lock_init(&ip->i_flags_lock);
/*
* Get pointer's to the on-disk inode and the buffer containing it.
@ -2214,7 +2215,9 @@ xfs_ifree_cluster(
if (ip == free_ip) {
if (xfs_iflock_nowait(ip)) {
spin_lock(&ip->i_flags_lock);
ip->i_flags |= XFS_ISTALE;
spin_unlock(&ip->i_flags_lock);
if (xfs_inode_clean(ip)) {
xfs_ifunlock(ip);
@ -2228,7 +2231,9 @@ xfs_ifree_cluster(
if (xfs_ilock_nowait(ip, XFS_ILOCK_EXCL)) {
if (xfs_iflock_nowait(ip)) {
spin_lock(&ip->i_flags_lock);
ip->i_flags |= XFS_ISTALE;
spin_unlock(&ip->i_flags_lock);
if (xfs_inode_clean(ip)) {
xfs_ifunlock(ip);
@ -2258,7 +2263,9 @@ xfs_ifree_cluster(
AIL_LOCK(mp,s);
iip->ili_flush_lsn = iip->ili_item.li_lsn;
AIL_UNLOCK(mp, s);
spin_lock(&iip->ili_inode->i_flags_lock);
iip->ili_inode->i_flags |= XFS_ISTALE;
spin_unlock(&iip->ili_inode->i_flags_lock);
pre_flushed++;
}
lip = lip->li_bio_list;
@ -2754,19 +2761,29 @@ xfs_iunpin(
* call as the inode reclaim may be blocked waiting for
* the inode to become unpinned.
*/
struct inode *inode = NULL;
spin_lock(&ip->i_flags_lock);
if (!(ip->i_flags & (XFS_IRECLAIM|XFS_IRECLAIMABLE))) {
bhv_vnode_t *vp = XFS_ITOV_NULL(ip);
/* make sync come back and flush this inode */
if (vp) {
struct inode *inode = vn_to_inode(vp);
inode = vn_to_inode(vp);
if (!(inode->i_state &
(I_NEW|I_FREEING|I_CLEAR)))
(I_NEW|I_FREEING|I_CLEAR))) {
inode = igrab(inode);
if (inode)
mark_inode_dirty_sync(inode);
} else
inode = NULL;
}
}
spin_unlock(&ip->i_flags_lock);
wake_up(&ip->i_ipin_wait);
if (inode)
iput(inode);
}
}

1
fs/xfs/xfs_inode.h
View file

@ -267,6 +267,7 @@ typedef struct xfs_inode {
sema_t i_flock; /* inode flush lock */
atomic_t i_pincount; /* inode pin count */
wait_queue_head_t i_ipin_wait; /* inode pinning wait queue */
spinlock_t i_flags_lock; /* inode i_flags lock */
#ifdef HAVE_REFCACHE
struct xfs_inode **i_refcache; /* ptr to entry in ref cache */
struct xfs_inode *i_release; /* inode to unref */

1
fs/xfs/xfs_itable.c
View file

@ -577,6 +577,7 @@ xfs_bulkstat(
KM_SLEEP);
ip->i_ino = ino;
ip->i_mount = mp;
spin_lock_init(&ip->i_flags_lock);
if (bp)
xfs_buf_relse(bp);
error = xfs_itobp(mp, NULL, ip,

5
fs/xfs/xfs_vnodeops.c
View file

@ -3844,7 +3844,9 @@ xfs_reclaim(
XFS_MOUNT_ILOCK(mp);
vn_bhv_remove(VN_BHV_HEAD(vp), XFS_ITOBHV(ip));
list_add_tail(&ip->i_reclaim, &mp->m_del_inodes);
spin_lock(&ip->i_flags_lock);
ip->i_flags |= XFS_IRECLAIMABLE;
spin_unlock(&ip->i_flags_lock);
XFS_MOUNT_IUNLOCK(mp);
}
return 0;
@ -3869,8 +3871,10 @@ xfs_finish_reclaim(
* us.
*/
write_lock(&ih->ih_lock);
spin_lock(&ip->i_flags_lock);
if ((ip->i_flags & XFS_IRECLAIM) ||
(!(ip->i_flags & XFS_IRECLAIMABLE) && vp == NULL)) {
spin_unlock(&ip->i_flags_lock);
write_unlock(&ih->ih_lock);
if (locked) {
xfs_ifunlock(ip);
@ -3879,6 +3883,7 @@ xfs_finish_reclaim(
return 1;
}
ip->i_flags |= XFS_IRECLAIM;
spin_unlock(&ip->i_flags_lock);
write_unlock(&ih->ih_lock);
/*