GHSA-V5R3-WF29-QQ37
Vulnerability from github – Published: 2024-12-28 12:30 – Updated: 2025-11-03 21:32In the Linux kernel, the following vulnerability has been resolved:
powerpc/mm/fault: Fix kfence page fault reporting
copy_from_kernel_nofault() can be called when doing read of /proc/kcore. /proc/kcore can have some unmapped kfence objects which when read via copy_from_kernel_nofault() can cause page faults. Since *_nofault() functions define their own fixup table for handling fault, use that instead of asking kfence to handle such faults.
Hence we search the exception tables for the nip which generated the fault. If there is an entry then we let the fixup table handler handle the page fault by returning an error from within ___do_page_fault().
This can be easily triggered if someone tries to do dd from /proc/kcore. eg. dd if=/proc/kcore of=/dev/null bs=1M
Some example false negatives:
=============================== BUG: KFENCE: invalid read in copy_from_kernel_nofault+0x9c/0x1a0 Invalid read at 0xc0000000fdff0000: copy_from_kernel_nofault+0x9c/0x1a0 0xc00000000665f950 read_kcore_iter+0x57c/0xa04 proc_reg_read_iter+0xe4/0x16c vfs_read+0x320/0x3ec ksys_read+0x90/0x154 system_call_exception+0x120/0x310 system_call_vectored_common+0x15c/0x2ec
BUG: KFENCE: use-after-free read in copy_from_kernel_nofault+0x9c/0x1a0 Use-after-free read at 0xc0000000fe050000 (in kfence-#2): copy_from_kernel_nofault+0x9c/0x1a0 0xc00000000665f950 read_kcore_iter+0x57c/0xa04 proc_reg_read_iter+0xe4/0x16c vfs_read+0x320/0x3ec ksys_read+0x90/0x154 system_call_exception+0x120/0x310 system_call_vectored_common+0x15c/0x2ec
{
"affected": [],
"aliases": [
"CVE-2024-56678"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-12-28T10:15:08Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/mm/fault: Fix kfence page fault reporting\n\ncopy_from_kernel_nofault() can be called when doing read of /proc/kcore.\n/proc/kcore can have some unmapped kfence objects which when read via\ncopy_from_kernel_nofault() can cause page faults. Since *_nofault()\nfunctions define their own fixup table for handling fault, use that\ninstead of asking kfence to handle such faults.\n\nHence we search the exception tables for the nip which generated the\nfault. If there is an entry then we let the fixup table handler handle the\npage fault by returning an error from within ___do_page_fault().\n\nThis can be easily triggered if someone tries to do dd from /proc/kcore.\neg. dd if=/proc/kcore of=/dev/null bs=1M\n\nSome example false negatives:\n\n ===============================\n BUG: KFENCE: invalid read in copy_from_kernel_nofault+0x9c/0x1a0\n Invalid read at 0xc0000000fdff0000:\n copy_from_kernel_nofault+0x9c/0x1a0\n 0xc00000000665f950\n read_kcore_iter+0x57c/0xa04\n proc_reg_read_iter+0xe4/0x16c\n vfs_read+0x320/0x3ec\n ksys_read+0x90/0x154\n system_call_exception+0x120/0x310\n system_call_vectored_common+0x15c/0x2ec\n\n BUG: KFENCE: use-after-free read in copy_from_kernel_nofault+0x9c/0x1a0\n Use-after-free read at 0xc0000000fe050000 (in kfence-#2):\n copy_from_kernel_nofault+0x9c/0x1a0\n 0xc00000000665f950\n read_kcore_iter+0x57c/0xa04\n proc_reg_read_iter+0xe4/0x16c\n vfs_read+0x320/0x3ec\n ksys_read+0x90/0x154\n system_call_exception+0x120/0x310\n system_call_vectored_common+0x15c/0x2ec",
"id": "GHSA-v5r3-wf29-qq37",
"modified": "2025-11-03T21:32:01Z",
"published": "2024-12-28T12:30:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-56678"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/06dbbb4d5f7126b6307ab807cbf04ecfc459b933"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/15f78d2c3d1452645bd8b9da909b0ca266f83c43"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4d2655754e94741b159aa807b72ea85518a65fd5"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7eaeb7a49b6d16640f9f3c9074c05175d74c710b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9ea8d8bf9b625e8ad3be6b0432aecdc549914121"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e0a470b5733c1fe068d5c58b0bb91ad539604bc6"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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