On Tue, May 17, 2016 at 11:39:52AM +0200, David Sterba wrote: > On Mon, May 16, 2016 at 11:01:41AM -0700, Liu Bo wrote: > > On Sat, May 14, 2016 at 06:30:52PM +0800, Qu Wenruo wrote: > > > Hi Liu, > > > > > > Thanks for your patch first. > > > > > > On 05/14/2016 08:06 AM, Liu Bo wrote: > > > > Thanks to fuzz testing, we can pass an invalid bytenr to extent buffer > > > > via alloc_extent_buffer(). An unaligned eb can have more pages than it > > > > should have, which ends up extent buffer's leak or some corrupted > > > > content > > > > in extent buffer. > > > > > > > > This adds a warning to let us quickly know what was happening. > > > > > > > > Signed-off-by: Liu Bo <bo.li....@oracle.com> > > > > --- > > > > fs/btrfs/extent_io.c | 4 ++++ > > > > 1 file changed, 4 insertions(+) > > > > > > > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c > > > > index d247fc0..e601e0f 100644 > > > > --- a/fs/btrfs/extent_io.c > > > > +++ b/fs/btrfs/extent_io.c > > > > @@ -4868,6 +4868,10 @@ struct extent_buffer *alloc_extent_buffer(struct > > > > btrfs_fs_info *fs_info, > > > > int uptodate = 1; > > > > int ret; > > > > > > > > + WARN_ONCE(!IS_ALIGNED(start, fs_info->tree_root->sectorsize), > > > > + KERN_WARNING "eb->start(%llu) is not aligned to > > > > root->sectorsize(%u)\n", > > > > + start, fs_info->tree_root->sectorsize); > > > > + > > > > > > IMHO this is a quite big problem. As almost all other things rely on the > > > assumption that extent buffer are at least sectorsize aligned. > > > > It won't cause too much trouble as reading eb's page can prevent btrfs > > using this eb. > > > > > What about warning and returning NULL? WARN_ONCE() only won't info user > > > quick enough. > > > > I'm OK with warning, but I just realized that warning doesn't show which > > filesystem has problems, so btrfs_crit and -EINVAL is preferable. > > NULL means it's allocation error, so please convert it to IS_ERR and > return more fine grained errors so we can distinguish the problems. An > unaligned 'start' almost always means a corruption or other problem in > the callers of alloc_extent_buffer().
OK, sounds good. Thanks, -liubo -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
