[PATCH v3] ntfs: fix error handling in ntfs_extent_inode_open and propagate errors

[Baolin Liu]

From: Baolin Liu <liubaolin@xxxxxxxxxx>

ntfs_extent_inode_open() has two issues:

1. When map_mft_record() fails or a stale extent reference is found,
   it returns the non-NULL 'ni' pointer instead of an error, causing
   the caller to treat the failure as success.

2. For allocation failures, it returns NULL, losing information about
   what actually went wrong (-ENOMEM).

Fix both by converting the function to return ERR_PTR() on error, and
update the single caller (ntfs_inode_attach_all_extents) to check with
IS_ERR() and propagate the actual error code with PTR_ERR().

Fixes: af0db57d4293 ("ntfs: update inode operations")
Signed-off-by: Baolin Liu <liubaolin@xxxxxxxxxx>

---
Changes in v3:
- Return -EIO for stale extent MFT references.
- Call ntfs_destroy_ext_inode(ni) before returning ERR_PTR(-ENOMEM) on the
  kvzalloc() failure path, instead of overwriting ni first (Namjae Jeon)
- Drop the now unused err_out label
- Use ERR_CAST() instead of ERR_PTR(PTR_ERR())

Changes in v2:
- Convert ntfs_extent_inode_open() to return ERR_PTR() and update
  ntfs_inode_attach_all_extents() to use IS_ERR()/PTR_ERR()

 fs/ntfs/inode.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
index 5aedc045f65a..cf914e1ab0b7 100644
--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -2904,8 +2904,7 @@ int __ntfs_write_inode(struct inode *vi, int sync)
  * abort if deprotection or checks fail.
  *
  * Finally attach the ntfs inode to its base inode @base_ni and return a
- * pointer to the ntfs_inode structure on success or NULL on error, with errno
- * set to the error code.
+ * pointer to the ntfs_inode structure on success or ERR_PTR() on error.
  *
  * Note, extent inodes are never closed directly. They are automatically
  * disposed off by the closing of the base inode.
@@ -2921,7 +2920,7 @@ static struct ntfs_inode *ntfs_extent_inode_open(struct ntfs_inode *base_ni,
 	struct super_block *sb;
 
 	if (!base_ni)
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	sb = base_ni->vol->sb;
 	ntfs_debug("Opening extent inode %llu (base mft record %llu).\n",
@@ -2940,7 +2939,7 @@ static struct ntfs_inode *ntfs_extent_inode_open(struct ntfs_inode *base_ni,
 			if (IS_ERR(ni_mrec)) {
 				ntfs_error(sb, "failed to map mft record for %llu",
 						ni->mft_no);
-				goto out;
+				return ERR_CAST(ni_mrec);
 			}
 			/* Verify the sequence number if given. */
 			seq_no = MSEQNO_LE(mref);
@@ -2949,7 +2948,7 @@ static struct ntfs_inode *ntfs_extent_inode_open(struct ntfs_inode *base_ni,
 				ntfs_error(sb, "Found stale extent mft reference mft=%llu",
 						ni->mft_no);
 				unmap_mft_record(ni);
-				goto out;
+				return ERR_PTR(-EIO);
 			}
 			unmap_mft_record(ni);
 			goto out;
@@ -2958,7 +2957,7 @@ static struct ntfs_inode *ntfs_extent_inode_open(struct ntfs_inode *base_ni,
 	/* Wasn't there, we need to load the extent inode. */
 	ni = ntfs_new_extent_inode(base_ni->vol->sb, mft_no);
 	if (!ni)
-		goto out;
+		return ERR_PTR(-ENOMEM);
 
 	ni->seq_no = (u16)MSEQNO_LE(mref);
 	ni->nr_extents = -1;
@@ -2968,8 +2967,10 @@ static struct ntfs_inode *ntfs_extent_inode_open(struct ntfs_inode *base_ni,
 		i = (base_ni->nr_extents + 4) * sizeof(struct ntfs_inode *);
 
 		extent_nis = kvzalloc(i, GFP_NOFS);
-		if (!extent_nis)
-			goto err_out;
+		if (!extent_nis) {
+			ntfs_destroy_ext_inode(ni);
+			return ERR_PTR(-ENOMEM);
+		}
 		if (base_ni->nr_extents) {
 			memcpy(extent_nis, base_ni->ext.extent_ntfs_inos,
 					i - 4 * sizeof(struct ntfs_inode *));
@@ -2982,10 +2983,6 @@ static struct ntfs_inode *ntfs_extent_inode_open(struct ntfs_inode *base_ni,
 out:
 	ntfs_debug("\n");
 	return ni;
-err_out:
-	ntfs_destroy_ext_inode(ni);
-	ni = NULL;
-	goto out;
 }
 
 /*
@@ -3023,9 +3020,12 @@ int ntfs_inode_attach_all_extents(struct ntfs_inode *ni)
 	while ((u8 *)ale < ni->attr_list + ni->attr_list_size) {
 		if (ni->mft_no != MREF_LE(ale->mft_reference) &&
 				prev_attached != MREF_LE(ale->mft_reference)) {
-			if (!ntfs_extent_inode_open(ni, ale->mft_reference)) {
+			struct ntfs_inode *ext_ni;
+
+			ext_ni = ntfs_extent_inode_open(ni, ale->mft_reference);
+			if (IS_ERR(ext_ni)) {
 				ntfs_debug("Couldn't attach extent inode.\n");
-				return -1;
+				return PTR_ERR(ext_ni);
 			}
 			prev_attached = MREF_LE(ale->mft_reference);
 		}
-- 
2.51.0