fs: fix do_last error case when need_reval_dot

When open(2) without O_DIRECTORY opens an existing dir, it should return
EISDIR. In do_last(), the variable 'error' is initialized EISDIR, but it
is changed by d_revalidate() which returns any positive to represent
'the target dir is valid.'

Should we keep and return the initialized 'error' in this case.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

1 files changed, 6 insertions, 4 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 14c73edca9ce..bc24894c5f14 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2122,11 +2122,13 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
                 dir = nd->path.dentry;
         case LAST_DOT:
                 if (need_reval_dot(dir)) {
-                        error = d_revalidate(nd->path.dentry, nd);
-                        if (!error)
-                                error = -ESTALE;
-                        if (error < 0)
+                        int status = d_revalidate(nd->path.dentry, nd);
+                        if (!status)
+                                status = -ESTALE;
+                        if (status < 0) {
+                                error = status;
                                 goto exit;
+                        }
                 }
                 /* fallthrough */
         case LAST_ROOT: