High [CVE-2026-64026] Fix DATA decrypt vs splice by copying data to buffer in recvmsg

In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix DATA decrypt vs splice() by copying data to buffer in recvmsg This improves the fix for CVE-2026-43500.

Fix the pagecache corruption from in-place decryption of a DATA packet transmitted locally by splice() by getting rid of the packet sharing in the I/O thread and unconditionally extracting the packet content into a bounce buffer in which the buffer is decrypted. recvmsg() (or the kernel equivalent) then copies the data from the bounce buffer to the destination buffer.

The sk_buff then remains unmodified. This has an additional advantage in that the packet is then arranged in the buffer with the correct alignment required for the crypto algorithms to process directly.

The performance of the crypto does seem to be a little faster and, surprisingly, the unencrypted performance doesn't seem to change much - possibly due to removing complexity from the I/O thread. Yet another advantage is that the I/O thread doesn't have to copy packets which would slow down packet distribution, ACK generation, etc..

The buffer belongs to the call and is allocated initially at 2K, sufficiently large to hold a whole jumbo subpacket, but the buffer will be increased in size if needed.

Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9; Red Hat package: kernel-rt.