From: Theodore Ts'o tytso@mit.edu
[ Upstream commit 027f14f5357279655c3ebc6d14daff8368d4f53f ]
If we try to make any changes via the journal between when the journal is initialized, but before the multi-block allocated is initialized, we will end up deferencing a NULL pointer when the journal commit callback function calls ext4_process_freed_data().
The proximate cause of this failure was commit 2d01ddc86606 ("ext4: save error info to sb through journal if available") since file system corruption problems detected before the call to ext4_mb_init() would result in a journal commit before we aborted the mount of the file system.... and we would then trigger the NULL pointer deref.
Link: https://lore.kernel.org/r/YAm8qH/0oo2ofSMR@mit.edu Reported-by: Murphy Zhou jencce.kernel@gmail.com Reviewed-by: Jan Kara jack@suse.cz Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ext4/super.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 9a6f9875aa34..2ae0af1c88c7 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4875,7 +4875,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);
- sbi->s_journal->j_commit_callback = ext4_journal_commit_callback; sbi->s_journal->j_submit_inode_data_buffers = ext4_journal_submit_inode_data_buffers; sbi->s_journal->j_finish_inode_data_buffers = @@ -4987,6 +4986,14 @@ no_journal: goto failed_mount5; }
+ /* + * We can only set up the journal commit callback once + * mballoc is initialized + */ + if (sbi->s_journal) + sbi->s_journal->j_commit_callback = + ext4_journal_commit_callback; + block = ext4_count_free_clusters(sb); ext4_free_blocks_count_set(sbi->s_es, EXT4_C2B(sbi, block));