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| author | Anton Altaparmakov <anton@tuxera.com> | 2011-01-28 20:45:28 +0000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-31 12:58:11 +1000 |
| commit | af5eb745efe97d91d2cbe793029838b3311c15da (patch) | |
| tree | c2e410318a3f38928255ebf9ab18332b871e17f0 /fs/ntfs | |
| parent | 9fbf0c08d441888b977f7c459c8aa57f2c0cb6ad (diff) | |
| download | lwn-af5eb745efe97d91d2cbe793029838b3311c15da.tar.gz lwn-af5eb745efe97d91d2cbe793029838b3311c15da.zip | |
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')
| -rw-r--r-- | fs/ntfs/mft.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c index b572b6727181..326e7475a22a 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: flush_dcache_page(page); SetPageUptodate(page); 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( ~le16_to_cpu(MFT_RECORD_IN_USE)); @@ -2603,6 +2605,7 @@ mft_rec_already_initialized: ntfs_unmap_page(page); 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 |