Re: [PATCH] jffs2: fix double-free of f->target in jffs2_alloc_inode()

[Deepanshu Kartikey]

On Sat, Sep 12, 2026 at 12:28 PM Richard Weinberger <richard@xxxxxx> wrote:
>
> Am Sat, Sep 12, 2026, 03:08 schrieb Deepanshu Kartikey <kartikey406@xxxxxxxxx>:
>
> > On Sun, Aug 23, 2026 at 8:57 PM Deepanshu Kartikey
> > <kartikey406@xxxxxxxxx> wrote:
> > >
> > > jffs2_alloc_inode() does not initialize f->target before returning
> > > the new inode. It is normally cleared later by
> > > jffs2_init_inode_info(), called from jffs2_iget(), but that runs
> > > only after alloc_inode() has already returned successfully.
> > >
> > > If inode_init_always() fails in between, alloc_inode() calls
> > > ->free_inode() directly on the half-initialized inode.
> > > jffs2_free_inode() then does kfree(f->target) on whatever stale
> > > value was left in the reused slab object, which can be a pointer
> > > that was already freed, causing a double-free.
> > >
> > > Initialize f->target to NULL in jffs2_alloc_inode() to close this
> > > window, and clear it in jffs2_free_inode() after freeing it so a
> > > reused or re-freed object can never carry a dangling pointer.
> > >
> > > Fixes: 4fdcfab5b553 ("jffs2: fix use-after-free on symlink traversal")
> > > Reported-by: syzbot+675e84fdf3dde67b4946@xxxxxxxxxxxxxxxxxxxxxxxxx
> > > Closes: https://syzkaller.appspot.com/bug?extid=675e84fdf3dde67b4946
> > > Signed-off-by: Deepanshu Kartikey <kartikey406@xxxxxxxxx>
> > > ---
> > >  fs/jffs2/super.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
> > > index 81396a092ba8..30d753d4c263 100644
> > > --- a/fs/jffs2/super.c
> > > +++ b/fs/jffs2/super.c
> > > @@ -42,6 +42,7 @@ static struct inode *jffs2_alloc_inode(struct super_block *sb)
> > >         f = alloc_inode_sb(sb, jffs2_inode_cachep, GFP_KERNEL);
> > >         if (!f)
> > >                 return NULL;
> > > +       f->target = NULL;
> > >         return &f->vfs_inode;
> > >  }
> > >
> > > @@ -50,6 +51,7 @@ static void jffs2_free_inode(struct inode *inode)
> > >         struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
> > >
> > >         kfree(f->target);
> > > +       f->target = NULL;
> > >         kmem_cache_free(jffs2_inode_cachep, f);
> > >  }
> > >
> > > --
> > > 2.34.1
> > >
> >
> > Gentle Reminder. Please let me know the status of this patch.
>
> We got lot's of identical fixes this issue.
> I had no time yet to sort out who was the first.
> This is maybe the first report with fix suggestions, but the reporter
> vanished:
> https://lore.kernel.org/linux-mtd/CAFLxGvyZO_EDo-YM_EybZG3u7aNUoNiThhvbhQCrOPD7mPV6GA@xxxxxxxxxxxxxx/
>
> Thanks,
> //richard
>

I feel the patch you are pointing at fixes a different kind of issue ?