CVE-2021-47249 net: rds: fix memory leak in rds_recvmsg
A memory leak in the Linux kernel's RDS protocol allows attackers to cause a denial of service by exhausting system memory.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-47249?
CVE-2021-47249 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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 | }
Weakness: CWE-401
Which versions are affected by CVE-2021-47249?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47249?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-47249 being exploited?
There is no known exploitation of CVE-2021-47249 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47249, GHSA-prq2-qj2r-jcgv, UBUNTU-CVE-2021-47249.