CVE-2021-47249: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

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 | }

Affected products

• Linux Linux Kernel: from 2.6.30, before 4.4.274 (fixed in 4.4.274); from 4.5, before 4.9.274 (fixed in 4.9.274); from 4.10, before 4.14.238 (fixed in 4.14.238); from 4.15, before 4.19.196 (fixed in 4.19.196); from 4.20, before 5.4.128 (fixed in 5.4.128); from 5.5, before 5.10.46 (fixed in 5.10.46); …

Published 2024-05-21. Last modified 2026-06-17.