Re: Bug: slab-out-of-bounds Write in __bh_read

[Jan Kara]

On Fri 10-01-25 17:21:19, Kun Hu wrote:
> > 
> > OK. Checking the syzlang reproducer the same comment as for other
> > filesystem bugs applies - please run with CONFIG_BLK_DEV_WRITE_MOUNTED
> > disabled to rule out corruption of a filesystem while it is mounted.
> > 
> > 
> 
> Hi Jan,
> 
> We have reproduced the crash with CONFIG_BLK_DEV_WRITE_MOUNTED disabled
> to obtain the same crash log. The new crash log, along with C and Syzlang
> reproducers are provided below:
> 
> Crash log: https://drive.google.com/file/d/1FiCgo05oPheAt4sDQzRYTQwl0-CY6rvi/view?usp=sharing
> C reproducer: https://drive.google.com/file/d/1TTR9cquaJcMYER6vtYUGh3gOn_mROME4/view?usp=sharing
> Syzlang reproducer: https://drive.google.com/file/d/1R9QDUP2r7MI4kYMiT_yn-tzm6NqmcEW-/view?usp=sharing
> 
> I’m not sure if this is sufficient to help locate the bug? If you need
> additional information, please let me know.

Thanks. Based on the crash report and the reproducer it indeed looks like
some mixing of iomap_folio_state and buffer heads attached to a folio
(iomap_folio_state is attached there but we end up calling
__block_write_begin_int() which expects buffer heads there) in GFS2. GFS2
guys, care to have a look?

								Honza
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR