This is a note to let you know that I've just added the patch titled
reiserfs: add check for invalid 1st journal block
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
reiserfs-add-check-for-invalid-1st-journal-block.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b025a7bbb915d088d2a3afd88da94623839de63b
Author: Pavel Skripkin <paskripkin@xxxxxxxxx>
Date: Mon May 17 15:15:45 2021 +0300
reiserfs: add check for invalid 1st journal block
[ Upstream commit a149127be52fa7eaf5b3681a0317a2bbb772d5a9 ]
syzbot reported divide error in reiserfs.
The problem was in incorrect journal 1st block.
Syzbot's reproducer manualy generated wrong superblock
with incorrect 1st block. In journal_init() wasn't
any checks about this particular case.
For example, if 1st journal block is before superblock
1st block, it can cause zeroing important superblock members
in do_journal_end().
Link: https://lore.kernel.org/r/20210517121545.29645-1-paskripkin@xxxxxxxxx
Reported-by: syzbot+0ba9909df31c6a36974d@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 4b3e3e73b512..09ad022a78a5 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -2763,6 +2763,20 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
goto free_and_return;
}
+ /*
+ * Sanity check to see if journal first block is correct.
+ * If journal first block is invalid it can cause
+ * zeroing important superblock members.
+ */
+ if (!SB_ONDISK_JOURNAL_DEVICE(sb) &&
+ SB_ONDISK_JOURNAL_1st_BLOCK(sb) < SB_JOURNAL_1st_RESERVED_BLOCK(sb)) {
+ reiserfs_warning(sb, "journal-1393",
+ "journal 1st super block is invalid: 1st reserved block %d, but actual 1st block is %d",
+ SB_JOURNAL_1st_RESERVED_BLOCK(sb),
+ SB_ONDISK_JOURNAL_1st_BLOCK(sb));
+ goto free_and_return;
+ }
+
if (journal_init_dev(sb, journal, j_dev_name) != 0) {
reiserfs_warning(sb, "sh-462",
"unable to initialize journal device");
