path: root/fs/ntfs
diff options
authorAnton Altaparmakov <anton@tuxera.com>2011-01-28 20:45:28 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-31 12:58:11 +1000
commitaf5eb745efe97d91d2cbe793029838b3311c15da (patch)
treec2e410318a3f38928255ebf9ab18332b871e17f0 /fs/ntfs
parent9fbf0c08d441888b977f7c459c8aa57f2c0cb6ad (diff)
NTFS: Fix invalid pointer dereference in ntfs_mft_record_alloc().
In ntfs_mft_record_alloc() when mapping the new extent mft record with map_extent_mft_record() we overwrite @m with the return value and on error, we then try to use the old @m but that is no longer there as @m now contains an error code instead so we crash when dereferencing the error code as if it were a pointer. The simple fix is to use a temporary variable to store the return value thus preserving the original @m for later use. This is a backport from the commercial Tuxera-NTFS driver and is well tested... Thanks go to Julia Lawall for pointing this out (whilst I had fixed it in the commercial driver I had failed to fix it in the Linux kernel). Signed-off-by: Anton Altaparmakov <anton@tuxera.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/ntfs')
1 files changed, 7 insertions, 4 deletions
diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
index b572b672718..326e7475a22 100644
--- a/fs/ntfs/mft.c
+++ b/fs/ntfs/mft.c
@@ -1,7 +1,7 @@
* mft.c - NTFS kernel mft record operations. Part of the Linux-NTFS project.
- * Copyright (c) 2001-2006 Anton Altaparmakov
+ * Copyright (c) 2001-2011 Anton Altaparmakov and Tuxera Inc.
* Copyright (c) 2002 Richard Russon
* This program/include file is free software; you can redistribute it and/or
@@ -2576,6 +2576,8 @@ mft_rec_already_initialized:
if (base_ni) {
+ MFT_RECORD *m_tmp;
* Setup the base mft record in the extent mft record. This
* completes initialization of the allocated extent mft record
@@ -2588,11 +2590,11 @@ mft_rec_already_initialized:
* attach it to the base inode @base_ni and map, pin, and lock
* its, i.e. the allocated, mft record.
- m = map_extent_mft_record(base_ni, bit, &ni);
- if (IS_ERR(m)) {
+ m_tmp = map_extent_mft_record(base_ni, bit, &ni);
+ if (IS_ERR(m_tmp)) {
ntfs_error(vol->sb, "Failed to map allocated extent "
"mft record 0x%llx.", (long long)bit);
- err = PTR_ERR(m);
+ err = PTR_ERR(m_tmp);
/* Set the mft record itself not in use. */
m->flags &= cpu_to_le16(
@@ -2603,6 +2605,7 @@ mft_rec_already_initialized:
goto undo_mftbmp_alloc;
+ BUG_ON(m != m_tmp);
* Make sure the allocated mft record is written out to disk.
* No need to set the inode dirty because the caller is going