On Tue, Apr 21, 2020 at 12:43:15AM +0200, David Sterba wrote: > On Mon, Apr 20, 2020 at 01:38:40PM +0800, Xiyu Yang wrote: > > btrfs_remove_block_group() invokes btrfs_lookup_block_group(), which > > returns a local reference of the blcok group that contains the given > > bytenr to "block_group" with increased refcount. > > > > When btrfs_remove_block_group() returns, "block_group" becomes invalid, > > so the refcount should be decreased to keep refcount balanced. > > > > The reference counting issue happens in several exception handling paths > > of btrfs_remove_block_group(). When those error scenarios occur such as > > btrfs_alloc_path() returns NULL, the function forgets to decrease its > > refcnt increased by btrfs_lookup_block_group() and will cause a refcnt > > leak. > > > > Fix this issue by jumping to "out_put_group" label and calling > > btrfs_put_block_group() when those error scenarios occur. > > > > Signed-off-by: Xiyu Yang <xiyuyang19@xxxxxxxxxxxx> > > Signed-off-by: Xin Tan <tanxin.ctf@xxxxxxxxx> > > Thanks for the fix. May I ask if this was found by code inspection or by > some analysis tool? Thanks for your advice about the patch! We are looking for some automated ways to find this kind of bug.
