[RFC 1/1] fsnotify: next_i is freed during fsnotify_unmount_inodes.

From: Jerry Hoemann
Date: Wed Oct 08 2014 - 18:47:27 EST


During list_for_each_entry_safe, next_i is becoming free causing
the loop to never terminate. Advance next_i in those cases where
__iget is not done.

Signed-off-by: Jerry Hoemann <jerry.hoemann@xxxxxx>
---
fs/notify/inode_mark.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 9ce0622..e849714 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -288,20 +288,25 @@ void fsnotify_unmount_inodes(struct list_head *list)
spin_unlock(&inode->i_lock);

/* In case the dropping of a reference would nuke next_i. */
- if ((&next_i->i_sb_list != list) &&
- atomic_read(&next_i->i_count)) {
+ while (&next_i->i_sb_list != list) {
spin_lock(&next_i->i_lock);
- if (!(next_i->i_state & (I_FREEING | I_WILL_FREE))) {
+ if (!(next_i->i_state & (I_FREEING | I_WILL_FREE)) &&
+ atomic_read(&next_i->i_count)) {
__iget(next_i);
need_iput = next_i;
+ spin_unlock(&next_i->i_lock);
+ break;
}
spin_unlock(&next_i->i_lock);
+ next_i = list_entry(next_i->i_sb_list.next,
+ struct inode, i_sb_list);
}

/*
- * We can safely drop inode_sb_list_lock here because we hold
- * references on both inode and next_i. Also no new inodes
- * will be added since the umount has begun.
+ * We can safely drop inode_sb_list_lock here because either
+ * we actually hold references on both inode and next_i or
+ * end of list. Also no new inodes will be added since the
+ * umount has begun.
*/
spin_unlock(&inode_sb_list_lock);

--
1.7.11.3

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