Re: [PATCH V3 2/2] ocfs2: Fix uaf in ocfs2_set_buffer_uptodate

[Heming Zhao]

On 8/21/24 10:34, Joseph Qi wrote:
> And this is not a UAF case, but NULL pointer dereference.
> So I suggest change the subject to:
> ocfs2: fix possible NULL pointer dereference in ocfs2_set_buffer_uptodate

I agree with above too.
I didn't care about the patch subject in previous review jobs, 'UAF' is not suitable.

-Heming

> On 8/21/24 8:08 AM, Joseph Qi wrote:
> > On 8/20/24 5:45 PM, Lizhi Xu wrote:
> > > In the for-loop after the 'read_failure' label, the condition
> > > '(bh == NULL) && flags includes OCFS2_BH_READAHEAD' is missing.
> > > When this contidion is true, this for-loop will call ocfs2_set_buffer
> > > _uptodate(ci, bh), which then triggers a NULL pointer access error.
> >
> > Or it may simplified as the following:
> >
> > When doing cleanup, if flags without OCFS2_BH_READAHEAD, it may trigger
> > NULL pointer dereference in the following ocfs2_set_buffer_uptodate() if
> > bh is NULL.
> >
> > > Changes from V2:
> > > * Make the code more concise
> >
> > This is not the right place for changelog.
> >
> > Thanks,
> > Joseph
> >
> > > Reported-and-suggested-by: Heming Zhao <heming.zhao@xxxxxxxx>
> > > Signed-off-by: Lizhi Xu <lizhi.xu@xxxxxxxxxxxxx>
> > > Reviewed-by: Heming Zhao <heming.zhao@xxxxxxxx>
> > > ---
> > >   fs/ocfs2/buffer_head_io.c | 3 ++-
> > >   1 file changed, 2 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/ocfs2/buffer_head_io.c b/fs/ocfs2/buffer_head_io.c
> > > index e62c7e1de4eb..8f714406528d 100644
> > > --- a/fs/ocfs2/buffer_head_io.c
> > > +++ b/fs/ocfs2/buffer_head_io.c
> > > @@ -388,7 +388,8 @@ int ocfs2_read_blocks(struct ocfs2_caching_info *ci, u64 block, int nr,
> > >   		/* Always set the buffer in the cache, even if it was
> > >   		 * a forced read, or read-ahead which hasn't yet
> > >   		 * completed. */
> > > -		ocfs2_set_buffer_uptodate(ci, bh);
> > > +		if (bh)
> > > +			ocfs2_set_buffer_uptodate(ci, bh);
> > >   	}
> > >   	ocfs2_metadata_cache_io_unlock(ci);
> > >