Linus Torvalds intended to release Linux kernel 6.13 this Sunday, but the testing of branch 6.13 will likely be extended by a week due to stability issues with changes prepared by a Microsoft employee and accepted into branch 6.13 in November. Additionally, it is noted that the patch causing the failure was submitted in a non-standard way — but it was accepted, even though it did not receive any acknowledgments (ACK) from the maintainers of the x86 architecture, which violates accepted practices.
The patch added the capability to use large memory pages in ROX (Read Only Execute) mode when allocating memory intended for executable code. ROX allows the use of memory with executable code in read-only mode, complicating the exploitation of certain vulnerabilities. In kernel 6.13, the use of a cache of large executable memory pages reflected as ROX was enabled by default for executable module code on x86_64 systems. The change addressed the issue of mapping ROX pages for executable code that was not yet fully formed and eliminated the need for temporary remapping of ROX pages to write mode until the kernel modules were ready for operation.
At the final stage of testing the 6.13 kernel, an engineer from Intel identified a failure that prevents the kernel from correctly waking up from sleep mode on some laptops with Intel processors (for example, CPUs based on the Alder Lake microarchitecture). The failure manifested when the kernel was built with the Clang compiler with Control Flow Integrity (CFI) protection mode enabled, which blocks deviations from the normal execution order due to exploits that modify function pointers stored in memory. As a temporary solution, maintainers from Intel and AMD, responsible for the x86 architecture, suggested disabling EXECMEM_ROX usage in kernel 6.13 until a complete patch is prepared and tested to resolve the issue (the initial fix did not solve the problem).
Source: opennet.ru
