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CVE-2022-50838

UnknownEPSS 0.24%

Last modified

CVE-2022-50838 is a vulnerability of currently unknown severity. In the Linux kernel, the following vulnerability has been resolved: net: stream: purge sk_error_queue in sk_stream_kill_queues() Changheon Lee reported TCP socket leaks, with a nice repro. It seems we leak TCP sockets with the following sequence: 1) SOF_TIMESTAMPING_TX_ACK is enabled on the socket. Each ACK will cook an skb put in error queue, from __skb_tstamp_tx(). __skb_tstamp_tx() is using skb_clone(), unless SOF_TIMESTAMPING_OPT_TSONLY was also requested. 2) If the application is also using MSG_ZEROCOPY, then we put in the error queue cloned skbs that had a struct ubuf_info attached to them. Whenever an struct ubuf_info is allocated, sock_zerocopy_alloc() does a sock_hold(). As long as the cloned skbs are still in sk_error_queue, socket refcount is kept elevated. 3) Application closes the socket, while error queue is not empty. Since tcp_close() no longer purges the socket error queue, we might end up with a TCP socket with at least one skb in error queue keeping the socket alive forever. This bug can be (ab)used to consume all kernel memory and freeze the host. We need to purge the error queue, with proper synchronization against concurrent writers.. EPSS estimates a 0.24% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: net: stream: purge sk_error_queue in sk_stream_kill_queues() Changheon Lee reported TCP socket leaks, with a nice repro. It seems we leak TCP sockets with the following sequence: 1) SOF_TIMESTAMPING_TX_ACK is enabled on the socket. Each ACK will cook an skb put in error queue, from __skb_tstamp_tx(). __skb_tstamp_tx() is using skb_clone(), unless SOF_TIMESTAMPING_OPT_TSONLY was also requested. 2) If the application is also using MSG_ZEROCOPY, then we put in the error queue cloned skbs that had a struct ubuf_info attached to them. Whenever an struct ubuf_info is allocated, sock_zerocopy_alloc() does a sock_hold(). As long as the cloned skbs are still in sk_error_queue, socket refcount is kept elevated. 3) Application closes the socket, while error queue is not empty. Since tcp_close() no longer purges the socket error queue, we might end up with a TCP socket with at least one skb in error queue keeping the socket alive forever. This bug can be (ab)used to consume all kernel memory and freeze the host. We need to purge the error queue, with proper synchronization against concurrent writers.

Metrics

EPSS Probability
0.24%

14.9th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 7737b104c211fa843de268b897d601e070292a72, < c8c1eec578a9ae2dc8f14a1846942a0b7bf29d1d; >= 89be5c357de34718eaaaefed80737f432c5ab86f, < bab542cf56fc174c8447c00b73be99ffd66d2d39; >= 8b8b3d738e450d2c2ccdc75f0ab5a951746c2a96, < 6f00bd0402a1e3d2d556afba57c045bd7931e4d3; >= b631c603b5fb98d2bd709c35d384901965a3dd51, < 4f1d37ff4226eb99d6b69e9f4518e279e1a851bf; >= daf15fa1fd997749e881aedd9f03f73a11240e82, < 9062493811676ee0efe6c74d98f00ca38c4e17d4; >= 3988164fe9ddf98ebf5b5cdede91ac38c5f08a7e, < 9da204cd67c4fe97e8aa465d10d5c2e7076f7f42; >= 24bcbe1cc69fa52dc4f7b5b2456678ed464724d8, < 8c330c36b3970d0917f48827fa6c7a9c75aa4602; >= 24bcbe1cc69fa52dc4f7b5b2456678ed464724d8, < b458d349f8753f666233828ebd30df6f100cf7d5; >= 24bcbe1cc69fa52dc4f7b5b2456678ed464724d8, < e0c8bccd40fc1c19e1d246c39bcf79e357e1ada3; 6ba975e14f5ebb87143d737c493adf4031409a68; 4437f3ead9e85c35fe0e3adfb98c0b97eaa267eb; >= 4.9.291, < 4.9.337; >= 4.14.256, < 4.14.303; >= 4.19.218, < 4.19.270; >= 5.4.160, < 5.4.229; >= 5.10.80, < 5.10.163; >= 5.15.3, < 5.15.86; >= 4.4.293, < 4.5; >= 5.14.19, < 5.15
LinuxLinux5.16

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2022-50838?
In the Linux kernel, the following vulnerability has been resolved: net: stream: purge sk_error_queue in sk_stream_kill_queues() Changheon Lee reported TCP socket leaks, with a nice repro. It seems we leak TCP sockets with the following sequence: 1) SOF_TIMESTAMPING_TX_ACK is enabled on the socket. Each ACK will cook an skb put in error queue, from __skb_tstamp_tx(). __skb_tstamp_tx() is using skb_clone(), unless SOF_TIMESTAMPING_OPT_TSONLY was also requested. 2) If the application is also using MSG_ZEROCOPY, then we put in the error queue cloned skbs that had a struct ubuf_info attached to them. Whenever an struct ubuf_info is allocated, sock_zerocopy_alloc() does a sock_hold(). As long as the cloned skbs are still in sk_error_queue, socket refcount is kept elevated. 3) Application closes the socket, while error queue is not empty. Since tcp_close() no longer purges the socket error queue, we might end up with a TCP socket with at least one skb in error queue keeping the socket alive forever. This bug can be (ab)used to consume all kernel memory and freeze the host. We need to purge the error queue, with proper synchronization against concurrent writers.
How severe is CVE-2022-50838?
Severity scoring for CVE-2022-50838 is pending analysis. The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.
How do I fix CVE-2022-50838?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST