GHSA-H79V-798M-6JC3

Vulnerability from github – Published: 2024-10-21 12:30 – Updated: 2024-10-24 15:31
VLAI
Details

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

ARM: 9410/1: vfp: Use asm volatile in fmrx/fmxr macros

Floating point instructions in userspace can crash some arm kernels built with clang/LLD 17.0.6:

BUG: unsupported FP instruction in kernel mode
FPEXC == 0xc0000780
Internal error: Oops - undefined instruction: 0 [#1] ARM
CPU: 0 PID: 196 Comm: vfp-reproducer Not tainted 6.10.0 #1
Hardware name: BCM2835
PC is at vfp_support_entry+0xc8/0x2cc
LR is at do_undefinstr+0xa8/0x250
pc : [<c0101d50>]    lr : [<c010a80c>]    psr: a0000013
sp : dc8d1f68  ip : 60000013  fp : bedea19c
r10: ec532b17  r9 : 00000010  r8 : 0044766c
r7 : c0000780  r6 : ec532b17  r5 : c1c13800  r4 : dc8d1fb0
r3 : c10072c4  r2 : c0101c88  r1 : ec532b17  r0 : 0044766c
Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 00c5387d  Table: 0251c008  DAC: 00000051
Register r0 information: non-paged memory
Register r1 information: vmalloc memory
Register r2 information: non-slab/vmalloc memory
Register r3 information: non-slab/vmalloc memory
Register r4 information: 2-page vmalloc region
Register r5 information: slab kmalloc-cg-2k
Register r6 information: vmalloc memory
Register r7 information: non-slab/vmalloc memory
Register r8 information: non-paged memory
Register r9 information: zero-size pointer
Register r10 information: vmalloc memory
Register r11 information: non-paged memory
Register r12 information: non-paged memory
Process vfp-reproducer (pid: 196, stack limit = 0x61aaaf8b)
Stack: (0xdc8d1f68 to 0xdc8d2000)
1f60:                   0000081f b6f69300 0000000f c10073f4 c10072c4 dc8d1fb0
1f80: ec532b17 0c532b17 0044766c b6f9ccd8 00000000 c010a80c 00447670 60000010
1fa0: ffffffff c1c13800 00c5387d c0100f10 b6f68af8 00448fc0 00000000 bedea188
1fc0: bedea314 00000001 00448ebc b6f9d000 00447608 b6f9ccd8 00000000 bedea19c
1fe0: bede9198 bedea188 b6e1061c 0044766c 60000010 ffffffff 00000000 00000000
Call trace:
[<c0101d50>] (vfp_support_entry) from [<c010a80c>] (do_undefinstr+0xa8/0x250)
[<c010a80c>] (do_undefinstr) from [<c0100f10>] (__und_usr+0x70/0x80)
Exception stack(0xdc8d1fb0 to 0xdc8d1ff8)
1fa0:                                     b6f68af8 00448fc0 00000000 bedea188
1fc0: bedea314 00000001 00448ebc b6f9d000 00447608 b6f9ccd8 00000000 bedea19c
1fe0: bede9198 bedea188 b6e1061c 0044766c 60000010 ffffffff
Code: 0a000061 e3877202 e594003c e3a09010 (eef16a10)
---[ end trace 0000000000000000 ]---
Kernel panic - not syncing: Fatal exception in interrupt
---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---

This is a minimal userspace reproducer on a Raspberry Pi Zero W:

#include <stdio.h>
#include <math.h>

int main(void)
{
        double v = 1.0;
        printf("%fn", NAN + *(volatile double *)&v);
        return 0;
}

Another way to consistently trigger the oops is:

calvin@raspberry-pi-zero-w ~$ python -c "import json"

The bug reproduces only when the kernel is built with DYNAMIC_DEBUG=n, because the pr_debug() calls act as barriers even when not activated.

This is the output from the same kernel source built with the same compiler and DYNAMIC_DEBUG=y, where the userspace reproducer works as expected:

VFP: bounce: trigger ec532b17 fpexc c0000780
VFP: emulate: INST=0xee377b06 SCR=0x00000000
VFP: bounce: trigger eef1fa10 fpexc c0000780
VFP: emulate: INST=0xeeb40b40 SCR=0x00000000
VFP: raising exceptions 30000000

calvin@raspberry-pi-zero-w ~$ ./vfp-reproducer
nan

Crudely grepping for vmsr/vmrs instructions in the otherwise nearly idential text for vfp_support_entry() makes the problem obvious:

vmlinux.llvm.good [0xc0101cb8] <+48>:  vmrs   r7, fpexc
vmlinux.llvm.good [0xc0101cd8] <+80>:  vmsr   fpexc, r0
vmlinux.llvm.good [0xc0101d20

---truncated---

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2024-47716"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-10-21T12:15:07Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nARM: 9410/1: vfp: Use asm volatile in fmrx/fmxr macros\n\nFloating point instructions in userspace can crash some arm kernels\nbuilt with clang/LLD 17.0.6:\n\n    BUG: unsupported FP instruction in kernel mode\n    FPEXC == 0xc0000780\n    Internal error: Oops - undefined instruction: 0 [#1] ARM\n    CPU: 0 PID: 196 Comm: vfp-reproducer Not tainted 6.10.0 #1\n    Hardware name: BCM2835\n    PC is at vfp_support_entry+0xc8/0x2cc\n    LR is at do_undefinstr+0xa8/0x250\n    pc : [\u003cc0101d50\u003e]    lr : [\u003cc010a80c\u003e]    psr: a0000013\n    sp : dc8d1f68  ip : 60000013  fp : bedea19c\n    r10: ec532b17  r9 : 00000010  r8 : 0044766c\n    r7 : c0000780  r6 : ec532b17  r5 : c1c13800  r4 : dc8d1fb0\n    r3 : c10072c4  r2 : c0101c88  r1 : ec532b17  r0 : 0044766c\n    Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none\n    Control: 00c5387d  Table: 0251c008  DAC: 00000051\n    Register r0 information: non-paged memory\n    Register r1 information: vmalloc memory\n    Register r2 information: non-slab/vmalloc memory\n    Register r3 information: non-slab/vmalloc memory\n    Register r4 information: 2-page vmalloc region\n    Register r5 information: slab kmalloc-cg-2k\n    Register r6 information: vmalloc memory\n    Register r7 information: non-slab/vmalloc memory\n    Register r8 information: non-paged memory\n    Register r9 information: zero-size pointer\n    Register r10 information: vmalloc memory\n    Register r11 information: non-paged memory\n    Register r12 information: non-paged memory\n    Process vfp-reproducer (pid: 196, stack limit = 0x61aaaf8b)\n    Stack: (0xdc8d1f68 to 0xdc8d2000)\n    1f60:                   0000081f b6f69300 0000000f c10073f4 c10072c4 dc8d1fb0\n    1f80: ec532b17 0c532b17 0044766c b6f9ccd8 00000000 c010a80c 00447670 60000010\n    1fa0: ffffffff c1c13800 00c5387d c0100f10 b6f68af8 00448fc0 00000000 bedea188\n    1fc0: bedea314 00000001 00448ebc b6f9d000 00447608 b6f9ccd8 00000000 bedea19c\n    1fe0: bede9198 bedea188 b6e1061c 0044766c 60000010 ffffffff 00000000 00000000\n    Call trace:\n    [\u003cc0101d50\u003e] (vfp_support_entry) from [\u003cc010a80c\u003e] (do_undefinstr+0xa8/0x250)\n    [\u003cc010a80c\u003e] (do_undefinstr) from [\u003cc0100f10\u003e] (__und_usr+0x70/0x80)\n    Exception stack(0xdc8d1fb0 to 0xdc8d1ff8)\n    1fa0:                                     b6f68af8 00448fc0 00000000 bedea188\n    1fc0: bedea314 00000001 00448ebc b6f9d000 00447608 b6f9ccd8 00000000 bedea19c\n    1fe0: bede9198 bedea188 b6e1061c 0044766c 60000010 ffffffff\n    Code: 0a000061 e3877202 e594003c e3a09010 (eef16a10)\n    ---[ end trace 0000000000000000 ]---\n    Kernel panic - not syncing: Fatal exception in interrupt\n    ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---\n\nThis is a minimal userspace reproducer on a Raspberry Pi Zero W:\n\n    #include \u003cstdio.h\u003e\n    #include \u003cmath.h\u003e\n\n    int main(void)\n    {\n            double v = 1.0;\n            printf(\"%fn\", NAN + *(volatile double *)\u0026v);\n            return 0;\n    }\n\nAnother way to consistently trigger the oops is:\n\n    calvin@raspberry-pi-zero-w ~$ python -c \"import json\"\n\nThe bug reproduces only when the kernel is built with DYNAMIC_DEBUG=n,\nbecause the pr_debug() calls act as barriers even when not activated.\n\nThis is the output from the same kernel source built with the same\ncompiler and DYNAMIC_DEBUG=y, where the userspace reproducer works as\nexpected:\n\n    VFP: bounce: trigger ec532b17 fpexc c0000780\n    VFP: emulate: INST=0xee377b06 SCR=0x00000000\n    VFP: bounce: trigger eef1fa10 fpexc c0000780\n    VFP: emulate: INST=0xeeb40b40 SCR=0x00000000\n    VFP: raising exceptions 30000000\n\n    calvin@raspberry-pi-zero-w ~$ ./vfp-reproducer\n    nan\n\nCrudely grepping for vmsr/vmrs instructions in the otherwise nearly\nidential text for vfp_support_entry() makes the problem obvious:\n\n    vmlinux.llvm.good [0xc0101cb8] \u003c+48\u003e:  vmrs   r7, fpexc\n    vmlinux.llvm.good [0xc0101cd8] \u003c+80\u003e:  vmsr   fpexc, r0\n    vmlinux.llvm.good [0xc0101d20\n---truncated---",
  "id": "GHSA-h79v-798m-6jc3",
  "modified": "2024-10-24T15:31:08Z",
  "published": "2024-10-21T12:30:56Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-47716"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/39caf610a63786b3b0ef3348ac015edc19827d6a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/89a906dfa8c3b21b3e5360f73c49234ac1eb885b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9fc60f2bdd43e758bdf0305c0fc83221419ddb3f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cd595d87e5fdd2fc09ea69359aa85e7f12f4b97b"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.


Loading…

Loading…

Loading…

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Loading…

Loading…

Loading…

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.


Loading…