CVE-2026-64048 (GCVE-0-2026-64048)
Vulnerability from cvelistv5
Published
2026-07-19 15:39
Modified
2026-08-23 12:45
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net/smc: reject CHID-0 ACCEPT that matches an empty ism_dev slot On the SMC-D client, slot 0 of ini->ism_dev[]/ini->ism_chid[] is reserved for an SMC-Dv1 device. smc_find_ism_v2_device_clnt() populates V2 entries starting at index 1, so when no V1 device is selected slot 0 is left in its kzalloc()'ed state with ism_dev[0] == NULL and ism_chid[0] == 0. smc_v2_determine_accepted_chid() then matches the peer's CHID against the array starting from index 0 using the CHID alone. A malicious peer replying to a SMC-Dv2-only proposal with d1.chid == 0 matches the empty slot, ini->ism_selected becomes 0, and the subsequent ism_dev[0]->lgr_lock dereference in smc_conn_create() faults at offsetof(struct smcd_dev, lgr_lock) == 0x68: BUG: KASAN: null-ptr-deref in _raw_spin_lock_bh+0x79/0xe0 Write of size 4 at addr 0000000000000068 by task exploit/144 Call Trace: _raw_spin_lock_bh smc_conn_create (net/smc/smc_core.c:1997) __smc_connect (net/smc/af_smc.c:1447) smc_connect (net/smc/af_smc.c:1720) __sys_connect __x64_sys_connect do_syscall_64 Require ism_dev[i] to be non-NULL before accepting a CHID match.
References
Impacted products
Vendor Product Version
Linux Linux Version: a7c9c5f4af7f6098da68705fc5d86565d0728ef7
Version: a7c9c5f4af7f6098da68705fc5d86565d0728ef7
Version: a7c9c5f4af7f6098da68705fc5d86565d0728ef7
Version: a7c9c5f4af7f6098da68705fc5d86565d0728ef7
Version: a7c9c5f4af7f6098da68705fc5d86565d0728ef7
Version: a7c9c5f4af7f6098da68705fc5d86565d0728ef7
Version: a7c9c5f4af7f6098da68705fc5d86565d0728ef7
Version: a7c9c5f4af7f6098da68705fc5d86565d0728ef7
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/smc/af_smc.c"
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          "product": "Linux",
          "programFiles": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "0",
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              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
        {
          "nodes": [
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: reject CHID-0 ACCEPT that matches an empty ism_dev slot\n\nOn the SMC-D client, slot 0 of ini-\u003eism_dev[]/ini-\u003eism_chid[] is\nreserved for an SMC-Dv1 device. smc_find_ism_v2_device_clnt()\npopulates V2 entries starting at index 1, so when no V1 device is\nselected slot 0 is left in its kzalloc()\u0027ed state with ism_dev[0] ==\nNULL and ism_chid[0] == 0.\n\nsmc_v2_determine_accepted_chid() then matches the peer\u0027s CHID against\nthe array starting from index 0 using the CHID alone. A malicious\npeer replying to a SMC-Dv2-only proposal with d1.chid == 0 matches\nthe empty slot, ini-\u003eism_selected becomes 0, and the subsequent\nism_dev[0]-\u003elgr_lock dereference in smc_conn_create() faults at\noffsetof(struct smcd_dev, lgr_lock) == 0x68:\n\n  BUG: KASAN: null-ptr-deref in _raw_spin_lock_bh+0x79/0xe0\n  Write of size 4 at addr 0000000000000068 by task exploit/144\n  Call Trace:\n   _raw_spin_lock_bh\n   smc_conn_create (net/smc/smc_core.c:1997)\n   __smc_connect (net/smc/af_smc.c:1447)\n   smc_connect (net/smc/af_smc.c:1720)\n   __sys_connect\n   __x64_sys_connect\n   do_syscall_64\n\nRequire ism_dev[i] to be non-NULL before accepting a CHID match."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The fault is triggered while processing a malicious CLC ACCEPT message received from a remote TCP peer during the SMC-D handshake; the attacker controls the server response over the network.\nAC:L - Once a victim with SMC-Dv2 hardware initiates an SMC connection, a malicious peer can reliably send `d1.chid == 0` in the CLC ACCEPT to match the empty reserved slot 0 without races or special timing.\nPR:N - No local privileges are required on the victim host; an unauthenticated remote attacker operating a malicious SMC server can crash connecting clients, and unprivileged users can create SMC sockets without capability checks.\nUI:N - Exploitation requires only that a victim application initiate a normal outbound SMC connection to the attacker\u0027s server, which occurs automatically in enterprise middleware without per-connection user action.\nS:U - The vulnerability causes a kernel crash on the victim host but does not cross a security boundary such as VM escape or sandbox breakout.\nC:N - The bug is a null pointer dereference when taking `ism_dev[0]-\u003elgr_lock`; it causes an immediate kernel fault with no information disclosure.\nI:N - The attempted write at address 0x68 is a spinlock operation on a NULL `smcd_dev` pointer, not a controlled or arbitrary memory modification primitive.\nA:H - A successful trigger causes a kernel null pointer dereference (KASAN-reported oops/panic), crashing the affected system or at minimum the connecting process\u0027s kernel context."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-23T12:45:32.597Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/903f7688ffeb9b323d70652c01f554bd4ba2a3d6"
        },
        {
          "url": "https://git.kernel.org/stable/c/dd2f9dd83c68abd7ba7ded7075290b016cb7ecd0"
        },
        {
          "url": "https://git.kernel.org/stable/c/6927cacf2b10d4fa80c1a2d407512ef9397c59c6"
        },
        {
          "url": "https://git.kernel.org/stable/c/d38ba387244e5c5f7db3e11ea98bc2c7beccb0c0"
        },
        {
          "url": "https://git.kernel.org/stable/c/53eb7bd09aace72fa17510d80e0caf5ca058c231"
        },
        {
          "url": "https://git.kernel.org/stable/c/afa9036b8c9963947b487c36e332df6a42c96fcb"
        },
        {
          "url": "https://git.kernel.org/stable/c/65edb3b0822cfe5041be8fbabebd57e2e5ad9f4e"
        },
        {
          "url": "https://git.kernel.org/stable/c/277740023def559a4a2ddc3e8e784ee37a0f16a9"
        }
      ],
      "title": "net/smc: reject CHID-0 ACCEPT that matches an empty ism_dev slot",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64048",
    "datePublished": "2026-07-19T15:39:32.664Z",
    "dateReserved": "2026-07-19T07:54:57.029Z",
    "dateUpdated": "2026-08-23T12:45:32.597Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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