Re: [PATCH] jfs: fix array-index-out-of-bounds

[Ghanshyam Agrawal]

On Sun, Sep 22, 2024 at 8:35 PM Christophe JAILLET
<christophe.jaillet@xxxxxxxxxx> wrote:
>
> Le 22/09/2024 à 13:00, Ghanshyam Agrawal a écrit :
> > In some cases, dn_numag may be greater than MAXAG which may
> > result in an array-index-out-of-bounds in dbNextAG. Added
> > a check to return an error code before we crash.
> >
> > Reported-by: syzbot+808f3f84407f08a93022@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Closes: https://syzkaller.appspot.com/bug?extid=808f3f84407f08a93022
> > Signed-off-by: Ghanshyam Agrawal <ghanshyam1898@xxxxxxxxx>
> > ---
> >   fs/jfs/jfs_imap.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
> > index 2ec35889ad24..5088da13e8f1 100644
> > --- a/fs/jfs/jfs_imap.c
> > +++ b/fs/jfs/jfs_imap.c
> > @@ -1360,6 +1360,9 @@ int diAlloc(struct inode *pip, bool dir, struct inode *ip)
> >       if (agno < 0 || agno > dn_numag)
> >               return -EIO;
> >
> > +     if (unlikely(dn_numag > MAXAG))
>
> Hi,
>
> looking at other places with checks with MAXAG, I wonder if it should be >=?
>
> CJ
>
> > +             return -EIO;
> > +
> >       if (atomic_read(&JFS_SBI(pip->i_sb)->bmap->db_active[agno])) {
> >               /*
> >                * There is an open file actively growing.  We want to
>

Hello Christophe,

Thanks for reviewing my code. I believe the greater than symbol I have
set is correct in this case. Can you please check it thoroughly and let
me know wny it should be >= ?

Thanks & Regards,
Ghanshyam Agrawal