Re: [PATCH] ext3/4: fix uninitialized bs in ext3/4_xattr_set_handle()

[Eric Sandeen <sandeen@redhat.com>]

Tiger Yang wrote:
> Hi, Eric,
> 
> I don't have tesecase about this bug. I did the test manually. I use 
> khexedit to confirm the attributes whether in inody or block.
> The problem about this bug is we want to replace an existing attribute 
> in ibody with big size value which larger than free space in ibody.
> Because we didn't do block_find(), so the struct bs have not been 
> initialized. Then when we try to set attribute in block by block_set(), 
> we find bs->base is empty, we need alloc a new block for attributes. The 
> old block pointed by i_file_acl will lost with attributes in it.

Thanks, I'll go for a reproducer.  We use xattrs a lot for selinux in
Red Hat and Fedora, so a little surprised I haven't seen this bug... or
maybe it explains some bugs I haven't yet figured out ... :)

Thanks,
-Eric