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authorJan Kara <jack@suse.cz>2009-02-10 11:15:34 -0500
committerTheodore Tso <tytso@mit.edu>2009-02-10 11:15:34 -0500
commit7f5aa215088b817add9c71914b83650bdd49f8a9 (patch)
tree9b811d1f0b41a2738fc68654ae605bf5d8cf2a72 /fs/ext4
parent9eddacf9e9c03578ef2c07c9534423e823d677f8 (diff)
downloadlinux-7f5aa215088b817add9c71914b83650bdd49f8a9.tar.bz2
jbd2: Avoid possible NULL dereference in jbd2_journal_begin_ordered_truncate()
If we race with commit code setting i_transaction to NULL, we could possibly dereference it. Proper locking requires the journal pointer (to access journal->j_list_lock), which we don't have. So we have to change the prototype of the function so that filesystem passes us the journal pointer. Also add a more detailed comment about why the function jbd2_journal_begin_ordered_truncate() does what it does and how it should be used. Thanks to Dan Carpenter <error27@gmail.com> for pointing to the suspitious code. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Acked-by: Joel Becker <joel.becker@oracle.com> CC: linux-ext4@vger.kernel.org CC: ocfs2-devel@oss.oracle.com CC: mfasheh@suse.de CC: Dan Carpenter <error27@gmail.com>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/inode.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 03ba20be1329..658c4a7f2578 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -47,8 +47,10 @@
static inline int ext4_begin_ordered_truncate(struct inode *inode,
loff_t new_size)
{
- return jbd2_journal_begin_ordered_truncate(&EXT4_I(inode)->jinode,
- new_size);
+ return jbd2_journal_begin_ordered_truncate(
+ EXT4_SB(inode->i_sb)->s_journal,
+ &EXT4_I(inode)->jinode,
+ new_size);
}
static void ext4_invalidatepage(struct page *page, unsigned long offset);