| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 100/188] reiserfs: add check for invalid 1st journal block | Date | Mon, 19 Jul 2021 16:51:24 +0200 |
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From: Pavel Skripkin <paskripkin@gmail.com>
[ 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@gmail.com Reported-by: syzbot+0ba9909df31c6a36974d@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Sasha Levin <sashal@kernel.org> --- fs/reiserfs/journal.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c index 00985f9db9f7..6a0fa0cdc1ed 100644 --- a/fs/reiserfs/journal.c +++ b/fs/reiserfs/journal.c @@ -2770,6 +2770,20 @@ 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"); -- 2.30.2
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