CVE-2026-23143 (GCVE-0-2026-23143)

Vulnerability from cvelistv5 – Published: 2026-02-14 15:36 – Updated: 2026-02-14 15:36
VLAI?
Title
virtio_net: Fix misalignment bug in struct virtnet_info
Summary
In the Linux kernel, the following vulnerability has been resolved: virtio_net: Fix misalignment bug in struct virtnet_info Use the new TRAILING_OVERLAP() helper to fix a misalignment bug along with the following warning: drivers/net/virtio_net.c:429:46: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] This helper creates a union between a flexible-array member (FAM) and a set of members that would otherwise follow it (in this case `u8 rss_hash_key_data[VIRTIO_NET_RSS_MAX_KEY_SIZE];`). This overlays the trailing members (rss_hash_key_data) onto the FAM (hash_key_data) while keeping the FAM and the start of MEMBERS aligned. The static_assert() ensures this alignment remains. Notice that due to tail padding in flexible `struct virtio_net_rss_config_trailer`, `rss_trailer.hash_key_data` (at offset 83 in struct virtnet_info) and `rss_hash_key_data` (at offset 84 in struct virtnet_info) are misaligned by one byte. See below: struct virtio_net_rss_config_trailer { __le16 max_tx_vq; /* 0 2 */ __u8 hash_key_length; /* 2 1 */ __u8 hash_key_data[]; /* 3 0 */ /* size: 4, cachelines: 1, members: 3 */ /* padding: 1 */ /* last cacheline: 4 bytes */ }; struct virtnet_info { ... struct virtio_net_rss_config_trailer rss_trailer; /* 80 4 */ /* XXX last struct has 1 byte of padding */ u8 rss_hash_key_data[40]; /* 84 40 */ ... /* size: 832, cachelines: 13, members: 48 */ /* sum members: 801, holes: 8, sum holes: 31 */ /* paddings: 2, sum paddings: 5 */ }; After changes, those members are correctly aligned at offset 795: struct virtnet_info { ... union { struct virtio_net_rss_config_trailer rss_trailer; /* 792 4 */ struct { unsigned char __offset_to_hash_key_data[3]; /* 792 3 */ u8 rss_hash_key_data[40]; /* 795 40 */ }; /* 792 43 */ }; /* 792 44 */ ... /* size: 840, cachelines: 14, members: 47 */ /* sum members: 801, holes: 8, sum holes: 35 */ /* padding: 4 */ /* paddings: 1, sum paddings: 4 */ /* last cacheline: 8 bytes */ }; As a result, the RSS key passed to the device is shifted by 1 byte: the last byte is cut off, and instead a (possibly uninitialized) byte is added at the beginning. As a last note `struct virtio_net_rss_config_hdr *rss_hdr;` is also moved to the end, since it seems those three members should stick around together. :)
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: ed3100e90d0d120a045a551b85eb43cf2527e885 , < ae48108c2310f1dd700e0dbb655c2f1d92ed00fc (git)
Affected: ed3100e90d0d120a045a551b85eb43cf2527e885 , < 4156c3745f06bc197094b9ee97a9584e69ed00bf (git)
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    Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 6.18.7 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/virtio_net.c"
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          "vendor": "Linux",
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              "versionType": "git"
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          "vendor": "Linux",
          "versions": [
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              "status": "unaffected",
              "version": "6.19",
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.7",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvirtio_net: Fix misalignment bug in struct virtnet_info\n\nUse the new TRAILING_OVERLAP() helper to fix a misalignment bug\nalong with the following warning:\n\ndrivers/net/virtio_net.c:429:46: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]\n\nThis helper creates a union between a flexible-array member (FAM)\nand a set of members that would otherwise follow it (in this case\n`u8 rss_hash_key_data[VIRTIO_NET_RSS_MAX_KEY_SIZE];`). This\noverlays the trailing members (rss_hash_key_data) onto the FAM\n(hash_key_data) while keeping the FAM and the start of MEMBERS aligned.\nThe static_assert() ensures this alignment remains.\n\nNotice that due to tail padding in flexible `struct\nvirtio_net_rss_config_trailer`, `rss_trailer.hash_key_data`\n(at offset 83 in struct virtnet_info) and `rss_hash_key_data` (at\noffset 84 in struct virtnet_info) are misaligned by one byte. See\nbelow:\n\nstruct virtio_net_rss_config_trailer {\n        __le16                     max_tx_vq;            /*     0     2 */\n        __u8                       hash_key_length;      /*     2     1 */\n        __u8                       hash_key_data[];      /*     3     0 */\n\n        /* size: 4, cachelines: 1, members: 3 */\n        /* padding: 1 */\n        /* last cacheline: 4 bytes */\n};\n\nstruct virtnet_info {\n...\n        struct virtio_net_rss_config_trailer rss_trailer; /*    80     4 */\n\n        /* XXX last struct has 1 byte of padding */\n\n        u8                         rss_hash_key_data[40]; /*    84    40 */\n...\n        /* size: 832, cachelines: 13, members: 48 */\n        /* sum members: 801, holes: 8, sum holes: 31 */\n        /* paddings: 2, sum paddings: 5 */\n};\n\nAfter changes, those members are correctly aligned at offset 795:\n\nstruct virtnet_info {\n...\n        union {\n                struct virtio_net_rss_config_trailer rss_trailer; /*   792     4 */\n                struct {\n                        unsigned char __offset_to_hash_key_data[3]; /*   792     3 */\n                        u8         rss_hash_key_data[40]; /*   795    40 */\n                };                                       /*   792    43 */\n        };                                               /*   792    44 */\n...\n        /* size: 840, cachelines: 14, members: 47 */\n        /* sum members: 801, holes: 8, sum holes: 35 */\n        /* padding: 4 */\n        /* paddings: 1, sum paddings: 4 */\n        /* last cacheline: 8 bytes */\n};\n\nAs a result, the RSS key passed to the device is shifted by 1\nbyte: the last byte is cut off, and instead a (possibly\nuninitialized) byte is added at the beginning.\n\nAs a last note `struct virtio_net_rss_config_hdr *rss_hdr;` is also\nmoved to the end, since it seems those three members should stick\naround together. :)"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-14T15:36:08.834Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ae48108c2310f1dd700e0dbb655c2f1d92ed00fc"
        },
        {
          "url": "https://git.kernel.org/stable/c/4156c3745f06bc197094b9ee97a9584e69ed00bf"
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      "title": "virtio_net: Fix misalignment bug in struct virtnet_info",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23143",
    "datePublished": "2026-02-14T15:36:08.834Z",
    "dateReserved": "2026-01-13T15:37:45.973Z",
    "dateUpdated": "2026-02-14T15:36:08.834Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23143\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-02-14T16:15:54.383\",\"lastModified\":\"2026-02-14T16:15:54.383\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nvirtio_net: Fix misalignment bug in struct virtnet_info\\n\\nUse the new TRAILING_OVERLAP() helper to fix a misalignment bug\\nalong with the following warning:\\n\\ndrivers/net/virtio_net.c:429:46: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]\\n\\nThis helper creates a union between a flexible-array member (FAM)\\nand a set of members that would otherwise follow it (in this case\\n`u8 rss_hash_key_data[VIRTIO_NET_RSS_MAX_KEY_SIZE];`). This\\noverlays the trailing members (rss_hash_key_data) onto the FAM\\n(hash_key_data) while keeping the FAM and the start of MEMBERS aligned.\\nThe static_assert() ensures this alignment remains.\\n\\nNotice that due to tail padding in flexible `struct\\nvirtio_net_rss_config_trailer`, `rss_trailer.hash_key_data`\\n(at offset 83 in struct virtnet_info) and `rss_hash_key_data` (at\\noffset 84 in struct virtnet_info) are misaligned by one byte. See\\nbelow:\\n\\nstruct virtio_net_rss_config_trailer {\\n        __le16                     max_tx_vq;            /*     0     2 */\\n        __u8                       hash_key_length;      /*     2     1 */\\n        __u8                       hash_key_data[];      /*     3     0 */\\n\\n        /* size: 4, cachelines: 1, members: 3 */\\n        /* padding: 1 */\\n        /* last cacheline: 4 bytes */\\n};\\n\\nstruct virtnet_info {\\n...\\n        struct virtio_net_rss_config_trailer rss_trailer; /*    80     4 */\\n\\n        /* XXX last struct has 1 byte of padding */\\n\\n        u8                         rss_hash_key_data[40]; /*    84    40 */\\n...\\n        /* size: 832, cachelines: 13, members: 48 */\\n        /* sum members: 801, holes: 8, sum holes: 31 */\\n        /* paddings: 2, sum paddings: 5 */\\n};\\n\\nAfter changes, those members are correctly aligned at offset 795:\\n\\nstruct virtnet_info {\\n...\\n        union {\\n                struct virtio_net_rss_config_trailer rss_trailer; /*   792     4 */\\n                struct {\\n                        unsigned char __offset_to_hash_key_data[3]; /*   792     3 */\\n                        u8         rss_hash_key_data[40]; /*   795    40 */\\n                };                                       /*   792    43 */\\n        };                                               /*   792    44 */\\n...\\n        /* size: 840, cachelines: 14, members: 47 */\\n        /* sum members: 801, holes: 8, sum holes: 35 */\\n        /* padding: 4 */\\n        /* paddings: 1, sum paddings: 4 */\\n        /* last cacheline: 8 bytes */\\n};\\n\\nAs a result, the RSS key passed to the device is shifted by 1\\nbyte: the last byte is cut off, and instead a (possibly\\nuninitialized) byte is added at the beginning.\\n\\nAs a last note `struct virtio_net_rss_config_hdr *rss_hdr;` is also\\nmoved to the end, since it seems those three members should stick\\naround together. :)\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/4156c3745f06bc197094b9ee97a9584e69ed00bf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ae48108c2310f1dd700e0dbb655c2f1d92ed00fc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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