CVE-2024-27405 usb: gadget: ncm: Avoid dropping datagrams of properly parsed NTBs

2024-05-1711:40:25

Linux

www.cve.org

linux kernel

ncm

windows 11

datagrams

gadget_giveback

ntb

skb

u_ether

rx_list

lecroy

zlp

6.4 Medium

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

13.1%

JSON

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

usb: gadget: ncm: Avoid dropping datagrams of properly parsed NTBs

It is observed sometimes when tethering is used over NCM with Windows 11
as host, at some instances, the gadget_giveback has one byte appended at
the end of a proper NTB. When the NTB is parsed, unwrap call looks for
any leftover bytes in SKB provided by u_ether and if there are any pending
bytes, it treats them as a separate NTB and parses it. But in case the
second NTB (as per unwrap call) is faulty/corrupt, all the datagrams that
were parsed properly in the first NTB and saved in rx_list are dropped.

Adding a few custom traces showed the following:
[002] d…1 7828.532866: dwc3_gadget_giveback: ep1out:
req 000000003868811a length 1025/16384 zsI ==> 0
[002] d…1 7828.532867: ncm_unwrap_ntb: K: ncm_unwrap_ntb toprocess: 1025
[002] d…1 7828.532867: ncm_unwrap_ntb: K: ncm_unwrap_ntb nth: 1751999342
[002] d…1 7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb seq: 0xce67
[002] d…1 7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb blk_len: 0x400
[002] d…1 7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb ndp_len: 0x10
[002] d…1 7828.532869: ncm_unwrap_ntb: K: Parsed NTB with 1 frames

In this case, the giveback is of 1025 bytes and block length is 1024.
The rest 1 byte (which is 0x00) won’t be parsed resulting in drop of
all datagrams in rx_list.

Same is case with packets of size 2048:
[002] d…1 7828.557948: dwc3_gadget_giveback: ep1out:
req 0000000011dfd96e length 2049/16384 zsI ==> 0
[002] d…1 7828.557949: ncm_unwrap_ntb: K: ncm_unwrap_ntb nth: 1751999342
[002] d…1 7828.557950: ncm_unwrap_ntb: K: ncm_unwrap_ntb blk_len: 0x800

Lecroy shows one byte coming in extra confirming that the byte is coming
in from PC:

Transfer 2959 - Bytes Transferred(1025) Timestamp((18.524 843 590)

Transaction 8391 - Data(1025 bytes) Timestamp(18.524 843 590)
— Packet 4063861
Data(1024 bytes)
Duration(2.117us) Idle(14.700ns) Timestamp(18.524 843 590)
— Packet 4063863
Data(1 byte)
Duration(66.160ns) Time(282.000ns) Timestamp(18.524 845 722)

According to Windows driver, no ZLP is needed if wBlockLength is non-zero,
because the non-zero wBlockLength has already told the function side the
size of transfer to be expected. However, there are in-market NCM devices
that rely on ZLP as long as the wBlockLength is multiple of wMaxPacketSize.
To deal with such devices, it pads an extra 0 at end so the transfer is no
longer multiple of wMaxPacketSize.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/usb/gadget/function/f_ncm.c"
    ],
    "versions": [
      {
        "version": "9f6ce4240a2b",
        "lessThan": "059285e04ebb",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9f6ce4240a2b",
        "lessThan": "a31cf46d108d",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9f6ce4240a2b",
        "lessThan": "57ca0e16f393",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9f6ce4240a2b",
        "lessThan": "2cb66b62a5d6",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9f6ce4240a2b",
        "lessThan": "35b604a37ec7",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9f6ce4240a2b",
        "lessThan": "2b7ec68869d5",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9f6ce4240a2b",
        "lessThan": "c7f43900bc72",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9f6ce4240a2b",
        "lessThan": "76c51146820c",
        "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/usb/gadget/function/f_ncm.c"
    ],
    "versions": [
      {
        "version": "2.6.38",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "2.6.38",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.308",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.270",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.211",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.150",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.80",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.19",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7.7",
        "lessThanOrEqual": "6.7.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]