CVE-2021-47249

In the Linux kernel, the following vulnerability has been resolved: net:
rds: fix memory leak in rds_recvmsg Syzbot reported memory leak in rds. The
problem was in unputted refcount in case of error. int rds_recvmsg(struct
socket *sock, struct msghdr *msg, size_t size, int msg_flags) { … if
(!rds_next_incoming(rs, &inc)) { … } After this “if” inc refcount
incremented and if (rds_cmsg_recv(inc, msg, rs)) { ret = -EFAULT; goto out;
} … out: return ret; } in case of rds_cmsg_recv() fail the refcount won’t
be decremented. And it’s easy to see from ftrace log, that rds_inc_addref()
don’t have rds_inc_put() pair in rds_recvmsg() after rds_cmsg_recv() 1) |
rds_recvmsg() { 1) 3.721 us | rds_inc_addref(); 1) 3.853 us |
rds_message_inc_copy_to_user(); 1) + 10.395 us | rds_cmsg_recv(); 1) +
34.260 us | }