CVE-2025-39984 (GCVE-0-2025-39984)

Vulnerability from cvelistv5 – Published: 2025-10-15 07:56 – Updated: 2025-10-15 07:56
VLAI?
Title
net: tun: Update napi->skb after XDP process
Summary
In the Linux kernel, the following vulnerability has been resolved: net: tun: Update napi->skb after XDP process The syzbot report a UAF issue: BUG: KASAN: slab-use-after-free in skb_reset_mac_header include/linux/skbuff.h:3150 [inline] BUG: KASAN: slab-use-after-free in napi_frags_skb net/core/gro.c:723 [inline] BUG: KASAN: slab-use-after-free in napi_gro_frags+0x6e/0x1030 net/core/gro.c:758 Read of size 8 at addr ffff88802ef22c18 by task syz.0.17/6079 CPU: 0 UID: 0 PID: 6079 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Call Trace: <TASK> dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xca/0x240 mm/kasan/report.c:482 kasan_report+0x118/0x150 mm/kasan/report.c:595 skb_reset_mac_header include/linux/skbuff.h:3150 [inline] napi_frags_skb net/core/gro.c:723 [inline] napi_gro_frags+0x6e/0x1030 net/core/gro.c:758 tun_get_user+0x28cb/0x3e20 drivers/net/tun.c:1920 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> Allocated by task 6079: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:330 [inline] __kasan_mempool_unpoison_object+0xa0/0x170 mm/kasan/common.c:558 kasan_mempool_unpoison_object include/linux/kasan.h:388 [inline] napi_skb_cache_get+0x37b/0x6d0 net/core/skbuff.c:295 __alloc_skb+0x11e/0x2d0 net/core/skbuff.c:657 napi_alloc_skb+0x84/0x7d0 net/core/skbuff.c:811 napi_get_frags+0x69/0x140 net/core/gro.c:673 tun_napi_alloc_frags drivers/net/tun.c:1404 [inline] tun_get_user+0x77c/0x3e20 drivers/net/tun.c:1784 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6079: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:68 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576 poison_slab_object mm/kasan/common.c:243 [inline] __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275 kasan_slab_free include/linux/kasan.h:233 [inline] slab_free_hook mm/slub.c:2422 [inline] slab_free mm/slub.c:4695 [inline] kmem_cache_free+0x18f/0x400 mm/slub.c:4797 skb_pp_cow_data+0xdd8/0x13e0 net/core/skbuff.c:969 netif_skb_check_for_xdp net/core/dev.c:5390 [inline] netif_receive_generic_xdp net/core/dev.c:5431 [inline] do_xdp_generic+0x699/0x11a0 net/core/dev.c:5499 tun_get_user+0x2523/0x3e20 drivers/net/tun.c:1872 tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x5c9/0xb30 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f After commit e6d5dbdd20aa ("xdp: add multi-buff support for xdp running in generic mode"), the original skb may be freed in skb_pp_cow_data() when XDP program was attached, which was allocated in tun_napi_alloc_frags(). However, the napi->skb still point to the original skb, update it after XDP process.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: e6d5dbdd20aa6a86974af51deb9414cd2e7794cb , < 953200d56fc23eebf80a5ad9eed6e2e8a3065093 (git)
Affected: e6d5dbdd20aa6a86974af51deb9414cd2e7794cb , < 1697577e1669b0321d02cd848384a5d33e284296 (git)
Affected: e6d5dbdd20aa6a86974af51deb9414cd2e7794cb , < 1091860a16a86ccdd77c09f2b21a5f634f5ab9ec (git)
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    Linux Linux Affected: 6.9
Unaffected: 0 , < 6.9 (semver)
Unaffected: 6.12.50 , ≤ 6.12.* (semver)
Unaffected: 6.16.10 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/tun.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "953200d56fc23eebf80a5ad9eed6e2e8a3065093",
              "status": "affected",
              "version": "e6d5dbdd20aa6a86974af51deb9414cd2e7794cb",
              "versionType": "git"
            },
            {
              "lessThan": "1697577e1669b0321d02cd848384a5d33e284296",
              "status": "affected",
              "version": "e6d5dbdd20aa6a86974af51deb9414cd2e7794cb",
              "versionType": "git"
            },
            {
              "lessThan": "1091860a16a86ccdd77c09f2b21a5f634f5ab9ec",
              "status": "affected",
              "version": "e6d5dbdd20aa6a86974af51deb9414cd2e7794cb",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/tun.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "lessThan": "6.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.50",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16.10",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tun: Update napi-\u003eskb after XDP process\n\nThe syzbot report a UAF issue:\n\n  BUG: KASAN: slab-use-after-free in skb_reset_mac_header include/linux/skbuff.h:3150 [inline]\n  BUG: KASAN: slab-use-after-free in napi_frags_skb net/core/gro.c:723 [inline]\n  BUG: KASAN: slab-use-after-free in napi_gro_frags+0x6e/0x1030 net/core/gro.c:758\n  Read of size 8 at addr ffff88802ef22c18 by task syz.0.17/6079\n  CPU: 0 UID: 0 PID: 6079 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)\n  Call Trace:\n   \u003cTASK\u003e\n   dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120\n   print_address_description mm/kasan/report.c:378 [inline]\n   print_report+0xca/0x240 mm/kasan/report.c:482\n   kasan_report+0x118/0x150 mm/kasan/report.c:595\n   skb_reset_mac_header include/linux/skbuff.h:3150 [inline]\n   napi_frags_skb net/core/gro.c:723 [inline]\n   napi_gro_frags+0x6e/0x1030 net/core/gro.c:758\n   tun_get_user+0x28cb/0x3e20 drivers/net/tun.c:1920\n   tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996\n   new_sync_write fs/read_write.c:593 [inline]\n   vfs_write+0x5c9/0xb30 fs/read_write.c:686\n   ksys_write+0x145/0x250 fs/read_write.c:738\n   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   \u003c/TASK\u003e\n\n  Allocated by task 6079:\n   kasan_save_stack mm/kasan/common.c:47 [inline]\n   kasan_save_track+0x3e/0x80 mm/kasan/common.c:68\n   unpoison_slab_object mm/kasan/common.c:330 [inline]\n   __kasan_mempool_unpoison_object+0xa0/0x170 mm/kasan/common.c:558\n   kasan_mempool_unpoison_object include/linux/kasan.h:388 [inline]\n   napi_skb_cache_get+0x37b/0x6d0 net/core/skbuff.c:295\n   __alloc_skb+0x11e/0x2d0 net/core/skbuff.c:657\n   napi_alloc_skb+0x84/0x7d0 net/core/skbuff.c:811\n   napi_get_frags+0x69/0x140 net/core/gro.c:673\n   tun_napi_alloc_frags drivers/net/tun.c:1404 [inline]\n   tun_get_user+0x77c/0x3e20 drivers/net/tun.c:1784\n   tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996\n   new_sync_write fs/read_write.c:593 [inline]\n   vfs_write+0x5c9/0xb30 fs/read_write.c:686\n   ksys_write+0x145/0x250 fs/read_write.c:738\n   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\n  Freed by task 6079:\n   kasan_save_stack mm/kasan/common.c:47 [inline]\n   kasan_save_track+0x3e/0x80 mm/kasan/common.c:68\n   kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576\n   poison_slab_object mm/kasan/common.c:243 [inline]\n   __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275\n   kasan_slab_free include/linux/kasan.h:233 [inline]\n   slab_free_hook mm/slub.c:2422 [inline]\n   slab_free mm/slub.c:4695 [inline]\n   kmem_cache_free+0x18f/0x400 mm/slub.c:4797\n   skb_pp_cow_data+0xdd8/0x13e0 net/core/skbuff.c:969\n   netif_skb_check_for_xdp net/core/dev.c:5390 [inline]\n   netif_receive_generic_xdp net/core/dev.c:5431 [inline]\n   do_xdp_generic+0x699/0x11a0 net/core/dev.c:5499\n   tun_get_user+0x2523/0x3e20 drivers/net/tun.c:1872\n   tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996\n   new_sync_write fs/read_write.c:593 [inline]\n   vfs_write+0x5c9/0xb30 fs/read_write.c:686\n   ksys_write+0x145/0x250 fs/read_write.c:738\n   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nAfter commit e6d5dbdd20aa (\"xdp: add multi-buff support for xdp running in\ngeneric mode\"), the original skb may be freed in skb_pp_cow_data() when\nXDP program was attached, which was allocated in tun_napi_alloc_frags().\nHowever, the napi-\u003eskb still point to the original skb, update it after\nXDP process."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-10-15T07:56:03.438Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/953200d56fc23eebf80a5ad9eed6e2e8a3065093"
        },
        {
          "url": "https://git.kernel.org/stable/c/1697577e1669b0321d02cd848384a5d33e284296"
        },
        {
          "url": "https://git.kernel.org/stable/c/1091860a16a86ccdd77c09f2b21a5f634f5ab9ec"
        }
      ],
      "title": "net: tun: Update napi-\u003eskb after XDP process",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39984",
    "datePublished": "2025-10-15T07:56:03.438Z",
    "dateReserved": "2025-04-16T07:20:57.150Z",
    "dateUpdated": "2025-10-15T07:56:03.438Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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