CVE-2025-39682

Summary

In the Linux kernel, the following vulnerability has been resolved:tls: fix handling of zero-length records on the rx_listEach recvmsg() call must process either - only contiguous DATA records (any number of them) - one non-DATA recordIf the next record has different type than what has already been processed we break out of the main processing loop. If the record has already been decrypted (which may be the case for TLS 1.3 where we don't know type until decryption) we queue the pending record to the rx_list. Next recvmsg() will pick it up from there.Queuing the skb to rx_list after zero-copy decrypt is not possible, since in that case we decrypted directly to the user space buffer, and we don't have an skb to queue (darg.skb points to the ciphertext skb for access to metadata like length).Only data records are allowed zero-copy, and we break the processing loop after each non-data record. So we should never zero-copy and then find out that the record type has changed. The corner case we missed is when the initial record comes from rx_list, and it's zero length.

CWE-754Improper Check for Unusual or Exceptional Conditions

Attack profile

Affected products

• Linux84c61fe1a75b4255df1e1e7c054c9e6d048da417 to before 2902c3ebcca52ca845c03182000e8d71d3a5196f84c61fe1a75b4255df1e1e7c054c9e6d048da417 to before c09dd3773b5950e9cfb6c9b9a5f6e36d06c6267784c61fe1a75b4255df1e1e7c054c9e6d048da417 to before 3439c15ae91a517cf3c650ea15a8987699416ad984c61fe1a75b4255df1e1e7c054c9e6d048da417 to before 29c0ce3c8cdb6dc5d61139c937f34cb888a6f42e
• Linux6.0

References