CVE-2024-57838

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> s390/entry: Mark IRQ entries to fix stack depot warnings<br /> <br /> The stack depot filters out everything outside of the top interrupt<br /> context as an uninteresting or irrelevant part of the stack traces. This<br /> helps with stack trace de-duplication, avoiding an explosion of saved<br /> stack traces that share the same IRQ context code path but originate<br /> from different randomly interrupted points, eventually exhausting the<br /> stack depot.<br /> <br /> Filtering uses in_irqentry_text() to identify functions within the<br /> .irqentry.text and .softirqentry.text sections, which then become the<br /> last stack trace entries being saved.<br /> <br /> While __do_softirq() is placed into the .softirqentry.text section by<br /> common code, populating .irqentry.text is architecture-specific.<br /> <br /> Currently, the .irqentry.text section on s390 is empty, which prevents<br /> stack depot filtering and de-duplication and could result in warnings<br /> like:<br /> <br /> Stack depot reached limit capacity<br /> WARNING: CPU: 0 PID: 286113 at lib/stackdepot.c:252 depot_alloc_stack+0x39a/0x3c8<br /> <br /> with PREEMPT and KASAN enabled.<br /> <br /> Fix this by moving the IO/EXT interrupt handlers from .kprobes.text into<br /> the .irqentry.text section and updating the kprobes blacklist to include<br /> the .irqentry.text section.<br /> <br /> This is done only for asynchronous interrupts and explicitly not for<br /> program checks, which are synchronous and where the context beyond the<br /> program check is important to preserve. Despite machine checks being<br /> somewhat in between, they are extremely rare, and preserving context<br /> when possible is also of value.<br /> <br /> SVCs and Restart Interrupts are not relevant, one being always at the<br /> boundary to user space and the other being a one-time thing.<br /> <br /> IRQ entries filtering is also optionally used in ftrace function graph,<br /> where the same logic applies.