nouveau/dmem: Fix vulnerability in migrate_to_ram upon copy error

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: nouveau/dmem: Fix vulnerability in migrate_to_ram upon copy error The `nouveau_dmem_copy_one` function ensures that the copy push command is sent to the device firmware but does not track whether it was executed successfully. In the case of a copy error (e.g., firmware or hardware failure), the copy push command will be sent via the firmware channel, and `nouveau_dmem_copy_one` will likely report success, leading to the `migrate_to_ram` function returning a dirty HIGH_USER page to the user. This can result in a security vulnerability, as a HIGH_USER page that may contain sensitive or corrupted data could be returned to the user. To prevent this vulnerability, we allocate a zero page. Thus, in case of an error, a non-dirty (zero) page will be returned to the user.

References

• https://git.kernel.org/stable/c/fd9bb7e996bab9b9049fffe3f3d3b50dee191d27
• https://git.kernel.org/stable/c/73f75d2b5aee5a735cf64b8ab4543d5c20dbbdd9
• https://git.kernel.org/stable/c/8c3de9282dde21ce3c1bf1bde3166a4510547aa9
• https://git.kernel.org/stable/c/614bfb2050982d23d53d0d51c4079dba0437c883
• https://git.kernel.org/stable/c/697e3ddcf1f8b68bd531fc34eead27c000bdf3e1
• https://git.kernel.org/stable/c/ab4d113b6718b076046018292f821d5aa4b844f8
• https://git.kernel.org/stable/c/835745a377a4519decd1a36d6b926e369b3033e2