Re: [PATCH V3] ocfs2: add a sanity check for i_size

[Edward Adam Davis <eadavis@qq.com>]

On Wed, 16 Oct 2024 10:06:27 +0800, Joseph Qi wrote:
> > Reported-and-tested-by: syzbot+797d4829dafe3f11dce7@syzkaller.appspotmail.com
> > Closes: https://syzkaller.appspot.com/bug?extid=797d4829dafe3f11dce7
> > Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> > ---
> > V1 -> V2: keep rc to 0 when falgs contains READHEAD
> > V2 -> V3: check i_size only and alert subject and comments
> > 
> >  fs/ocfs2/extent_map.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > #syz test
> > 
> > diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
> > index f7672472fa82..29d27a70dbdd 100644
> > --- a/fs/ocfs2/extent_map.c
> > +++ b/fs/ocfs2/extent_map.c
> > @@ -961,13 +961,17 @@ int ocfs2_read_virt_blocks(struct inode *inode, u64 v_block, int nr,
> >  	int rc = 0;
> >  	u64 p_block, p_count;
> >  	int i, count, done = 0;
> > +	loff_t i_size = i_size_read(inode);
> >  
> >  	trace_ocfs2_read_virt_blocks(
> >  	     inode, (unsigned long long)v_block, nr, bhs, flags,
> >  	     validate);
> >  
> > +	if (!i_size)
> > +		return -EINVAL;
> > +
> 
> Take a more consideration, inode size 0 doesn't mean it has no blocks,
> since we have a case that fallocate with KEEP_SIZE.
> Could you please check inode->i_blocks in above coredump?
I have previously verified the value of inode->i_blocks in my testing environment, which is 0.

BR,
Edward