CVE-2024-50182

CVE Details

Release Date:

2024-11-08

Description

In the Linux kernel, the following vulnerability has been resolved:\nsecretmem: disable memfd_secret() if arch cannot set direct map\nReturn -ENOSYS from memfd_secret() syscall if !can_set_direct_map(). This\nis the case for example on some arm64 configurations, where marking 4k\nPTEs in the direct map not present can only be done if the direct map is\nset up at 4k granularity in the first place (as ARM's break-before-make\nsemantics do not easily allow breaking apart large/gigantic pages).\nMore precisely, on arm64 systems with !can_set_direct_map(),\nset_direct_map_invalid_noflush() is a no-op, however it returns success\n(0) instead of an error. This means that memfd_secret will seemingly\n'work' (e.g. syscall succeeds, you can mmap the fd and fault in pages),\nbut it does not actually achieve its goal of removing its memory from the\ndirect map.\nNote that with this patch, memfd_secret() will start erroring on systems\nwhere can_set_direct_map() returns false (arm64 with\nCONFIG_RODATA_FULL_DEFAULT_ENABLED=n, CONFIG_DEBUG_PAGEALLOC=n and\nCONFIG_KFENCE=n), but that still seems better than the current silent\nfailure. Since CONFIG_RODATA_FULL_DEFAULT_ENABLED defaults to 'y', most\narm64 systems actually have a working memfd_secret() and aren't be\naffected.\nFrom going through the iterations of the original memfd_secret patch\nseries, it seems that disabling the syscall in these scenarios was the\nintended behavior [1] (preferred over having\nset_direct_map_invalid_noflush return an error as that would result in\nSIGBUSes at page-fault time), however the check for it got dropped between\nv16 [2] and v17 [3], when secretmem moved away from CMA allocations.\n[1]: https://lore.kernel.org/lkml/20201124164930.GK8537@kernel.org/\n[2]: https://lore.kernel.org/lkml/20210121122723.3446-11-rppt@kernel.org/#t\n[3]: https://lore.kernel.org/lkml/20201125092208.12544-10-rppt@kernel.org/

See more information about CVE-2024-50182 from MITRE CVE dictionary and NIST NVD

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

CVSS v3 metrics

Base Score:	5.5
Vector String:	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Version:	3.1
Attack Vector:	Local
Attack Complexity:	Low
Privileges Required:	Low
User Interaction:	None
Scope:	Unchanged
Confidentiality:	None
Integrity:	None
Availability:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 8 (kernel-uek)	ELSA-2024-12887	2024-12-18
Oracle Linux version 9 (kernel-uek)	ELSA-2024-12887	2024-12-18