ghsa-g37w-wjp2-mp83
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
VMCI: Fix memcpy() run-time warning in dg_dispatch_as_host()
Syzkaller hit 'WARNING in dg_dispatch_as_host' bug.
memcpy: detected field-spanning write (size 56) of single field "&dg_info->msg" at drivers/misc/vmw_vmci/vmci_datagram.c:237 (size 24)
WARNING: CPU: 0 PID: 1555 at drivers/misc/vmw_vmci/vmci_datagram.c:237 dg_dispatch_as_host+0x88e/0xa60 drivers/misc/vmw_vmci/vmci_datagram.c:237
Some code commentry, based on my understanding:
544 #define VMCI_DG_SIZE(_dg) (VMCI_DG_HEADERSIZE + (size_t)(_dg)->payload_size) /// This is 24 + payload_size
memcpy(&dg_info->msg, dg, dg_size); Destination = dg_info->msg ---> this is a 24 byte structure(struct vmci_datagram) Source = dg --> this is a 24 byte structure (struct vmci_datagram) Size = dg_size = 24 + payload_size
{payload_size = 56-24 =32} -- Syzkaller managed to set payload_size to 32.
35 struct delayed_datagram_info { 36 struct datagram_entry entry; 37 struct work_struct work; 38 bool in_dg_host_queue; 39 / msg and msg_payload must be together. */ 40 struct vmci_datagram msg; 41 u8 msg_payload[]; 42 };
So those extra bytes of payload are copied into msg_payload[], a run time warning is seen while fuzzing with Syzkaller.
One possible way to fix the warning is to split the memcpy() into two parts -- one -- direct assignment of msg and second taking care of payload.
Gustavo quoted: "Under FORTIFY_SOURCE we should not copy data across multiple members in a structure."
{
"affected": [],
"aliases": [
"CVE-2024-35944"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-19T11:15:50Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nVMCI: Fix memcpy() run-time warning in dg_dispatch_as_host()\n\nSyzkaller hit \u0027WARNING in dg_dispatch_as_host\u0027 bug.\n\nmemcpy: detected field-spanning write (size 56) of single field \"\u0026dg_info-\u003emsg\"\nat drivers/misc/vmw_vmci/vmci_datagram.c:237 (size 24)\n\nWARNING: CPU: 0 PID: 1555 at drivers/misc/vmw_vmci/vmci_datagram.c:237\ndg_dispatch_as_host+0x88e/0xa60 drivers/misc/vmw_vmci/vmci_datagram.c:237\n\nSome code commentry, based on my understanding:\n\n544 #define VMCI_DG_SIZE(_dg) (VMCI_DG_HEADERSIZE + (size_t)(_dg)-\u003epayload_size)\n/// This is 24 + payload_size\n\nmemcpy(\u0026dg_info-\u003emsg, dg, dg_size);\n\tDestination = dg_info-\u003emsg ---\u003e this is a 24 byte\n\t\t\t\t\tstructure(struct vmci_datagram)\n\tSource = dg --\u003e this is a 24 byte structure (struct vmci_datagram)\n\tSize = dg_size = 24 + payload_size\n\n{payload_size = 56-24 =32} -- Syzkaller managed to set payload_size to 32.\n\n 35 struct delayed_datagram_info {\n 36 struct datagram_entry *entry;\n 37 struct work_struct work;\n 38 bool in_dg_host_queue;\n 39 /* msg and msg_payload must be together. */\n 40 struct vmci_datagram msg;\n 41 u8 msg_payload[];\n 42 };\n\nSo those extra bytes of payload are copied into msg_payload[], a run time\nwarning is seen while fuzzing with Syzkaller.\n\nOne possible way to fix the warning is to split the memcpy() into\ntwo parts -- one -- direct assignment of msg and second taking care of payload.\n\nGustavo quoted:\n\"Under FORTIFY_SOURCE we should not copy data across multiple members\nin a structure.\"",
"id": "GHSA-g37w-wjp2-mp83",
"modified": "2024-06-27T12:30:46Z",
"published": "2024-05-19T12:30:39Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35944"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/130b0cd064874e0d0f58e18fb00e6f3993e90c74"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/19b070fefd0d024af3daa7329cbc0d00de5302ec"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/491a1eb07c2bd8841d63cb5263455e185be5866f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ad78c5047dc4076d0b3c4fad4f42ffe9c86e8100"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dae70a57565686f16089737adb8ac64471570f73"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e87bb99d2df6512d8ee37a5d63d2ca9a39a8c051"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f15eca95138b3d4ec17b63c3c1937b0aa0d3624b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/feacd430b42bbfa9ab3ed9e4f38b86c43e348c75"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html"
}
],
"schema_version": "1.4.0",
"severity": []
}
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.