NTFS: Fix several bugs in fs/ntfs/attrib.c.

- Fix a bug in ntfs_map_runlist_nolock() where we forgot to protect
  access to the allocated size in the ntfs inode with the size lock.
- Fix ntfs_attr_vcn_to_lcn_nolock() and ntfs_attr_find_vcn_nolock() to
  return LCN_ENOENT when there is no runlist and the allocated size is
  zero.
- Fix load_attribute_list() to handle the case of a NULL runlist.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

2 files changed, 37 insertions, 1 deletions

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index 29841bf82264..1d1dcab3902c 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -60,6 +60,12 @@ ToDo/Notes:
           the index context.  Thanks to Yura Pakhuchiy for finding this bug.
         - Remove bogus setting of PageError in ntfs_read_compressed_block().
         - Add fs/ntfs/attrib.[hc]::ntfs_resident_attr_value_resize().
+        - Fix a bug in ntfs_map_runlist_nolock() where we forgot to protect
+          access to the allocated size in the ntfs inode with the size lock.
+        - Fix ntfs_attr_vcn_to_lcn_nolock() and ntfs_attr_find_vcn_nolock() to
+          return LCN_ENOENT when there is no runlist and the allocated size is
+          zero.
+        - Fix load_attribute_list() to handle the case of a NULL runlist.
 
 2.1.23 - Implement extension of resident files and make writing safe as well as
          many bug fixes, cleanups, and enhancements...
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 79dda3980684..98b5b96e8397 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -43,6 +43,9 @@
  * which is not an error as such.  This is -ENOENT.  It means that @vcn is out
  * of bounds of the runlist.
  *
+ * Note the runlist can be NULL after this function returns if @vcn is zero and
+ * the attribute has zero allocated size, i.e. there simply is no runlist.
+ *
  * Locking: - The runlist must be locked for writing.
  *          - This function modifies the runlist.
  */
@@ -54,6 +57,7 @@ int ntfs_map_runlist_nolock(ntfs_inode *ni, VCN vcn)
         ATTR_RECORD *a;
         ntfs_attr_search_ctx *ctx;
         runlist_element *rl;
+        unsigned long flags;
         int err = 0;
 
         ntfs_debug("Mapping runlist part containing vcn 0x%llx.",
@@ -85,8 +89,11 @@ int ntfs_map_runlist_nolock(ntfs_inode *ni, VCN vcn)
          * ntfs_mapping_pairs_decompress() fails.
          */
         end_vcn = sle64_to_cpu(a->data.non_resident.highest_vcn) + 1;
-        if (unlikely(!a->data.non_resident.lowest_vcn && end_vcn <= 1))
+        if (unlikely(!a->data.non_resident.lowest_vcn && end_vcn <= 1)) {
+                read_lock_irqsave(&ni->size_lock, flags);
                 end_vcn = ni->allocated_size >> ni->vol->cluster_size_bits;
+                read_unlock_irqrestore(&ni->size_lock, flags);
+        }
         if (unlikely(vcn >= end_vcn)) {
                 err = -ENOENT;
                 goto err_out;
@@ -165,6 +172,7 @@ LCN ntfs_attr_vcn_to_lcn_nolock(ntfs_inode *ni, const VCN vcn,
                 const BOOL write_locked)
 {
         LCN lcn;
+        unsigned long flags;
         BOOL is_retry = FALSE;
 
         ntfs_debug("Entering for i_ino 0x%lx, vcn 0x%llx, %s_locked.",
@@ -173,6 +181,14 @@ LCN ntfs_attr_vcn_to_lcn_nolock(ntfs_inode *ni, const VCN vcn,
         BUG_ON(!ni);
         BUG_ON(!NInoNonResident(ni));
         BUG_ON(vcn < 0);
+        if (!ni->runlist.rl) {
+                read_lock_irqsave(&ni->size_lock, flags);
+                if (!ni->allocated_size) {
+                        read_unlock_irqrestore(&ni->size_lock, flags);
+                        return LCN_ENOENT;
+                }
+                read_unlock_irqrestore(&ni->size_lock, flags);
+        }
 retry_remap:
         /* Convert vcn to lcn.  If that fails map the runlist and retry once. */
         lcn = ntfs_rl_vcn_to_lcn(ni->runlist.rl, vcn);
@@ -255,6 +271,7 @@ retry_remap:
 runlist_element *ntfs_attr_find_vcn_nolock(ntfs_inode *ni, const VCN vcn,
                 const BOOL write_locked)
 {
+        unsigned long flags;
         runlist_element *rl;
         int err = 0;
         BOOL is_retry = FALSE;
@@ -265,6 +282,14 @@ runlist_element *ntfs_attr_find_vcn_nolock(ntfs_inode *ni, const VCN vcn,
         BUG_ON(!ni);
         BUG_ON(!NInoNonResident(ni));
         BUG_ON(vcn < 0);
+        if (!ni->runlist.rl) {
+                read_lock_irqsave(&ni->size_lock, flags);
+                if (!ni->allocated_size) {
+                        read_unlock_irqrestore(&ni->size_lock, flags);
+                        return ERR_PTR(-ENOENT);
+                }
+                read_unlock_irqrestore(&ni->size_lock, flags);
+        }
 retry_remap:
         rl = ni->runlist.rl;
         if (likely(rl && vcn >= rl[0].vcn)) {
@@ -528,6 +553,11 @@ int load_attribute_list(ntfs_volume *vol, runlist *runlist, u8 *al_start,
         block_size_bits = sb->s_blocksize_bits;
         down_read(&runlist->lock);
         rl = runlist->rl;
+        if (!rl) {
+                ntfs_error(sb, "Cannot read attribute list since runlist is "
+                                "missing.");
+                goto err_out;   
+        }
         /* Read all clusters specified by the runlist one run at a time. */
         while (rl->length) {
                 lcn = ntfs_rl_vcn_to_lcn(rl, rl->vcn);