On Sun, 2021-03-14 at 09:36 +0100, Greg KH wrote: > On Sun, Mar 14, 2021 at 11:23:10AM +0300, Fatih Yildirim wrote: > > Hi Santosh, > > > > I've been working on a memory leak bug reported by syzbot. > > https://syzkaller.appspot.com/bug?id=39b72114839a6dbd66c1d2104522698a813f9ae2 > > > > It seems that memory allocated in rds_send_probe function is not > > freed. > > > > Let me share my observations. > > rds_message is allocated at the beginning of rds_send_probe > > function. > > Then it is added to cp_send_queue list of rds_conn_path and > > refcount > > is increased by one. > > Next, in rds_send_xmit function it is moved from cp_send_queue list > > to > > cp_retrans list, and again refcount is increased by one. > > Finally in rds_loop_xmit function refcount is increased by one. > > So, total refcount is 4. > > However, rds_message_put is called three times, in rds_send_probe, > > rds_send_remove_from_sock and rds_send_xmit functions. It seems > > that > > one more rds_message_put is needed. > > Would you please check and share your comments on this issue? > > Do you have a proposed patch that syzbot can test to verify if this > is > correct or not? > > thanks, > > gre gk-h Hi Greg, Actually, using the .config and the C reproducer, syzbot reports the memory leak in rds_send_probe function. Also by enabling CONFIG_RDS_DEBUG=y, the debug messages indicates the similar as I mentioned above. To give an example, below is the RDS_DEBUG messages. Allocated address 000000008a7476e5 has initial ref_count 1. Then there are three rds_message_addref calls for the same address making the refcount 4, but only three rds_message_put calls which leave the address still allocated. [ 60.570681] rds_message_addref(): addref rm 000000008a7476e5 ref 1 [ 60.570707] rds_message_put(): put rm 000000008a7476e5 ref 2 [ 60.570845] rds_message_addref(): addref rm 000000008a7476e5 ref 1 [ 60.570870] rds_message_addref(): addref rm 000000008a7476e5 ref 2 [ 60.570960] rds_message_put(): put rm 000000008a7476e5 ref 3 [ 60.570995] rds_message_put(): put rm 000000008a7476e5 ref 2 Thanks, Fatih
