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().
Reported-by: [email protected]
Signed-off-by: Pavel Skripkin <[email protected]>
---
Changes in v2:
Added necessary !SB_ONDISK_JOURNAL_DEVICE(sb) in "if"
---
fs/reiserfs/journal.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index 9edc8e2b154e..0834b101c316 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -2758,6 +2758,20 @@ 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");
--
2.31.1
On Mon 17-05-21 15:15:45, Pavel Skripkin wrote:
> 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().
>
> Reported-by: [email protected]
> Signed-off-by: Pavel Skripkin <[email protected]>
Thanks! I've added the patch to my tree.
Honza
> ---
>
> Changes in v2:
> Added necessary !SB_ONDISK_JOURNAL_DEVICE(sb) in "if"
>
> ---
> fs/reiserfs/journal.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
> index 9edc8e2b154e..0834b101c316 100644
> --- a/fs/reiserfs/journal.c
> +++ b/fs/reiserfs/journal.c
> @@ -2758,6 +2758,20 @@ 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");
> --
> 2.31.1
>
--
Jan Kara <[email protected]>
SUSE Labs, CR
On Tue 08-06-21 13:44:43, Pavel Skripkin wrote:
> On Mon, 17 May 2021 15:08:18 +0200
> Jan Kara <[email protected]> wrote:
>
> > On Mon 17-05-21 15:15:45, Pavel Skripkin wrote:
> > > 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().
> > >
> > > Reported-by: [email protected]
> > > Signed-off-by: Pavel Skripkin <[email protected]>
> >
> > Thanks! I've added the patch to my tree.
> >
> > Honza
> >
>
> Hi, Jan!
>
> Is this patched got lost somehow? I did't find it in your tree here
> https://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git/.
>
> Sorry to bother you, maybe Im missing something :)
It's sitting in my for_next branch as commit a149127be52f. I'll push it to
Linus in the coming merge window.
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR
On Mon, 17 May 2021 15:08:18 +0200
Jan Kara <[email protected]> wrote:
> On Mon 17-05-21 15:15:45, Pavel Skripkin wrote:
> > 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().
> >
> > Reported-by: [email protected]
> > Signed-off-by: Pavel Skripkin <[email protected]>
>
> Thanks! I've added the patch to my tree.
>
> Honza
>
Hi, Jan!
Is this patched got lost somehow? I did't find it in your tree here
https://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git/.
Sorry to bother you, maybe Im missing something :)
With regards,
Pavel Skripkin