We need to check i_count again with i_lock held, because iput might re-add
i_count when lazytime is on. Without this check, we could end up with
double-free or use-after-free.
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Chunwei Chen <david.chen@xxxxxxxxxxx>
---
fs/inode.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/inode.c b/fs/inode.c
index 4ccbc21..10bb020 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -607,7 +607,12 @@ again:
continue;
spin_lock(&inode->i_lock);
- if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
+ /*
+ * check i_count again with lock, because iput might re-add
+ * it when lazytime is on.
+ */
+ if (atomic_read(&inode->i_count) ||
+ (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE))) {
spin_unlock(&inode->i_lock);
continue;
}
--
2.7.4
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