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>
diff --git a/Documentation/filesystems/ntfs.txt b/Documentation/filesystems/ntfs.txt
index 6ef8cf3..933bc66 100644
--- a/Documentation/filesystems/ntfs.txt
+++ b/Documentation/filesystems/ntfs.txt
@@ -460,6 +460,8 @@
2.1.30:
- Fix writev() (it kept writing the first segment over and over again
instead of moving onto subsequent segments).
+ - Fix crash in ntfs_mft_record_alloc() when mapping the new extent mft
+ record failed.
2.1.29:
- Fix a deadlock when mounting read-write.
2.1.28: