[PATCH AUTOSEL 4.9 11/12] d_add_ci(): make sure we don't miss d_lookup_done()

[Sasha Levin <sashal@kernel.org>]

From: Al Viro <viro@zeniv.linux.org.uk>

[ Upstream commit 40a3cb0d2314a41975aa385a74643878454f6eac ]

All callers of d_alloc_parallel() must make sure that resulting
in-lookup dentry (if any) will encounter __d_lookup_done() before
the final dput().  d_add_ci() might end up creating in-lookup
dentries; they are fed to d_splice_alias(), which will normally
make sure they meet __d_lookup_done().  However, it is possible
to end up with d_splice_alias() failing with ERR_PTR(-ELOOP)
without having done so.  It takes a corrupted ntfs or case-insensitive
xfs image, but neither should end up with memory corruption...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/dcache.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index 05bad55352bb..e42c715fc9e9 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2089,6 +2089,7 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
 	}
 	res = d_splice_alias(inode, found);
 	if (res) {
+		d_lookup_done(found);
 		dput(found);
 		return res;
 	}
-- 
2.35.1