CVE-2024-42096

CVE Details

Release Date:

2024-07-29

Description

In the Linux kernel, the following vulnerability has been resolved:\nx86: stop playing stack games in profile_pc()\nThe 'profile_pc()' function is used for timer-based profiling, which\nisn't really all that relevant any more to begin with, but it also ends\nup making assumptions based on the stack layout that aren't necessarily\nvalid.\nBasically, the code tries to account the time spent in spinlocks to the\ncaller rather than the spinlock, and while I support that as a concept,\nit's not worth the code complexity or the KASAN warnings when no serious\nprofiling is done using timers anyway these days.\nAnd the code really does depend on stack layout that is only true in the\nsimplest of cases. We've lost the comment at some point (I think when\nthe 32-bit and 64-bit code was unified), but it used to say:\nAssume the lock function has either no stack frame or a copy\nof eflags from PUSHF.\nwhich explains why it just blindly loads a word or two straight off the\nstack pointer and then takes a minimal look at the values to just check\nif they might be eflags or the return pc:\nEflags always has bits 22 and up cleared unlike kernel addresses\nbut that basic stack layout assumption assumes that there isn't any lock\ndebugging etc going on that would complicate the code and cause a stack\nframe.\nIt causes KASAN unhappiness reported for years by syzkaller [1] and\nothers [2].\nWith no real practical reason for this any more, just remove the code.\nJust for historical interest, here's some background commits relating to\nthis code from 2006:\n0cb91a229364 ('i386: Account spinlocks to the caller during profiling for !FP kernels')\n31679f38d886 ('Simplify profile_pc on x86-64')\nand a code unification from 2009:\nef4512882dbe ('x86: time_32/64.c unify profile_pc')\nbut the basics of this thing actually goes back to before the git tree.

See more information about CVE-2024-42096 from MITRE CVE dictionary and NIST NVD

CVSS Scoring

NOTE: The following CVSS v3.1 metrics and score provided are preliminary and subject to review.

Base Score:	5.1	CVSS Vector:	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:H
Attack Vector:	Local network	Attack Complexity:	Low
Privileges Required:	High	User Interaction:	None
Scope:	Unchanged	Confidentiality Impact:	Low
Integrity Impact:	None	Availability Impact:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 7 (kernel-uek)	ELSA-2024-12610	2024-09-10
Oracle Linux version 7 (kernel-uek)	ELSA-2024-12779	2024-10-11
Oracle Linux version 7 (kernel-uek-container)	ELSA-2024-12612	2024-09-11
Oracle Linux version 8 (kernel)	ELSA-2024-7000	2024-09-24
Oracle Linux version 8 (kernel-uek)	ELSA-2024-12610	2024-09-10
Oracle Linux version 8 (kernel-uek)	ELSA-2024-12618	2024-09-12
Oracle Linux version 8 (kernel-uek-container)	ELSA-2024-12612	2024-09-11
Oracle Linux version 9 (kernel)	ELSA-2024-6567	2024-09-11
Oracle Linux version 9 (kernel-uek)	ELSA-2024-12618	2024-09-12