Linus Torvalds was planning to release the Linux kernel 6.13 this Sunday, but testing of branch 6.13 will most likely be extended by a week due to stability issues in the changes prepared by a Microsoft employee and adopted into branch 6.13 in November. Additionally, it was noted that the patch causing the failure was submitted in a non-standard way ā but was accepted, even though it did not receive a single acknowledgment (ACK) from the maintainers of the x86 architecture, which is a violation of accepted practices.
The patch added the ability 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 for large executable memory pages, reflected as ROX, was enabled by default for executable code modules on x86_64 systems. The change resolved the issue of mapping ROX pages for yet fully prepared executable code and eliminated the need for temporary remapping of ROX pages to write mode until the kernel modules were ready to operate.
At the final stage of testing kernel 6.13, an engineer from Intel discovered a failure that prevented the kernel from correctly waking from sleep mode on some laptops with Intel processors (for example, those with CPUs based on the Alder Lake microarchitecture). The failure manifested when the kernel was compiled using Clang with Control Flow Integrity (CFI) protection mode enabled, blocking deviations from the normal execution order (control flow) due to exploits altering 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 full patch that resolves the issue could be prepared and tested (the first fix option did not solve the problem).
Bron: opennet.ru
