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416baaa9-dc9f-4396-8d5f-8c081fb06d67CVE-2021-46927

HistoryFeb 27, 2024 - 10:15 a.m.

CVE-2021-46927

2024-02-2710:15:07

CWE-667

416baaa9-dc9f-4396-8d5f-8c081fb06d67

web.nvd.nist.gov

612

cve-2021-46927

linux kernel

nitro_enclaves

vulnerability

mmap assert

get_user_pages_unlocked

security advisory

5.5 Medium

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

6.2 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

9.1%

JSON

In the Linux kernel, the following vulnerability has been resolved:

nitro_enclaves: Use get_user_pages_unlocked() call to handle mmap assert

After commit 5b78ed24e8ec (“mm/pagemap: add mmap_assert_locked()
annotations to find_vma*()”), the call to get_user_pages() will trigger
the mmap assert.

static inline void mmap_assert_locked(struct mm_struct *mm)
{
lockdep_assert_held(&mm->mmap_lock);
VM_BUG_ON_MM(!rwsem_is_locked(&mm->mmap_lock), mm);
}

[ 62.521410] kernel BUG at include/linux/mmap_lock.h:156!
…
[ 62.538938] RIP: 0010:find_vma+0x32/0x80
…
[ 62.605889] Call Trace:
[ 62.608502] <TASK>
[ 62.610956] ? lock_timer_base+0x61/0x80
[ 62.614106] find_extend_vma+0x19/0x80
[ 62.617195] __get_user_pages+0x9b/0x6a0
[ 62.620356] __gup_longterm_locked+0x42d/0x450
[ 62.623721] ? finish_wait+0x41/0x80
[ 62.626748] ? __kmalloc+0x178/0x2f0
[ 62.629768] ne_set_user_memory_region_ioctl.isra.0+0x225/0x6a0 [nitro_enclaves]
[ 62.635776] ne_enclave_ioctl+0x1cf/0x6d7 [nitro_enclaves]
[ 62.639541] __x64_sys_ioctl+0x82/0xb0
[ 62.642620] do_syscall_64+0x3b/0x90
[ 62.645642] entry_SYSCALL_64_after_hwframe+0x44/0xae

Use get_user_pages_unlocked() when setting the enclave memory regions.
That’s a similar pattern as mmap_read_lock() used together with
get_user_pages().

Affected configurations

Vulners

NVD

Node

linuxlinux_kernelRange5.15–5.15.13

linuxlinux_kernelRange5.16.0≥

VendorProductVersionCPE
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

Vendor	Product	Version	CPE
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/virt/nitro_enclaves/ne_misc_dev.c"
    ],
    "versions": [
      {
        "version": "5b78ed24e8ec",
        "lessThan": "90d2beed5e75",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "5b78ed24e8ec",
        "lessThan": "3a0152b21952",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/virt/nitro_enclaves/ne_misc_dev.c"
    ],
    "versions": [
      {
        "version": "5.15",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.15",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.13",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.16",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]