ghsa-mmcv-ff9h-q89c
Vulnerability from github
Published
2025-09-15 15:31
Modified
2025-09-15 15:31
Details

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

bpf: make sure skb->len != 0 when redirecting to a tunneling device

syzkaller managed to trigger another case where skb->len == 0 when we enter __dev_queue_xmit:

WARNING: CPU: 0 PID: 2470 at include/linux/skbuff.h:2576 skb_assert_len include/linux/skbuff.h:2576 [inline] WARNING: CPU: 0 PID: 2470 at include/linux/skbuff.h:2576 __dev_queue_xmit+0x2069/0x35e0 net/core/dev.c:4295

Call Trace: dev_queue_xmit+0x17/0x20 net/core/dev.c:4406 __bpf_tx_skb net/core/filter.c:2115 [inline] __bpf_redirect_no_mac net/core/filter.c:2140 [inline] __bpf_redirect+0x5fb/0xda0 net/core/filter.c:2163 _bpfclone_redirect net/core/filter.c:2447 [inline] bpf_clone_redirect+0x247/0x390 net/core/filter.c:2419 bpf_prog_48159a89cb4a9a16+0x59/0x5e bpf_dispatcher_nop_func include/linux/bpf.h:897 [inline] bpf_prog_run include/linux/filter.h:596 [inline] bpf_prog_run include/linux/filter.h:603 [inline] bpf_test_run+0x46c/0x890 net/bpf/test_run.c:402 bpf_prog_test_run_skb+0xbdc/0x14c0 net/bpf/test_run.c:1170 bpf_prog_test_run+0x345/0x3c0 kernel/bpf/syscall.c:3648 __sys_bpf+0x43a/0x6c0 kernel/bpf/syscall.c:5005 __do_sys_bpf kernel/bpf/syscall.c:5091 [inline] __se_sys_bpf kernel/bpf/syscall.c:5089 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5089 do_syscall_64+0x54/0x70 arch/x86/entry/common.c:48 entry_SYSCALL_64_after_hwframe+0x61/0xc6

The reproducer doesn't really reproduce outside of syzkaller environment, so I'm taking a guess here. It looks like we do generate correct ETH_HLEN-sized packet, but we redirect the packet to the tunneling device. Before we do so, we __skb_pull l2 header and arrive again at skb->len == 0. Doesn't seem like we can do anything better than having an explicit check after __skb_pull?

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{
  "affected": [],
  "aliases": [
    "CVE-2022-50253"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-09-15T14:15:36Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: make sure skb-\u003elen != 0 when redirecting to a tunneling device\n\nsyzkaller managed to trigger another case where skb-\u003elen == 0\nwhen we enter __dev_queue_xmit:\n\nWARNING: CPU: 0 PID: 2470 at include/linux/skbuff.h:2576 skb_assert_len include/linux/skbuff.h:2576 [inline]\nWARNING: CPU: 0 PID: 2470 at include/linux/skbuff.h:2576 __dev_queue_xmit+0x2069/0x35e0 net/core/dev.c:4295\n\nCall Trace:\n dev_queue_xmit+0x17/0x20 net/core/dev.c:4406\n __bpf_tx_skb net/core/filter.c:2115 [inline]\n __bpf_redirect_no_mac net/core/filter.c:2140 [inline]\n __bpf_redirect+0x5fb/0xda0 net/core/filter.c:2163\n ____bpf_clone_redirect net/core/filter.c:2447 [inline]\n bpf_clone_redirect+0x247/0x390 net/core/filter.c:2419\n bpf_prog_48159a89cb4a9a16+0x59/0x5e\n bpf_dispatcher_nop_func include/linux/bpf.h:897 [inline]\n __bpf_prog_run include/linux/filter.h:596 [inline]\n bpf_prog_run include/linux/filter.h:603 [inline]\n bpf_test_run+0x46c/0x890 net/bpf/test_run.c:402\n bpf_prog_test_run_skb+0xbdc/0x14c0 net/bpf/test_run.c:1170\n bpf_prog_test_run+0x345/0x3c0 kernel/bpf/syscall.c:3648\n __sys_bpf+0x43a/0x6c0 kernel/bpf/syscall.c:5005\n __do_sys_bpf kernel/bpf/syscall.c:5091 [inline]\n __se_sys_bpf kernel/bpf/syscall.c:5089 [inline]\n __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5089\n do_syscall_64+0x54/0x70 arch/x86/entry/common.c:48\n entry_SYSCALL_64_after_hwframe+0x61/0xc6\n\nThe reproducer doesn\u0027t really reproduce outside of syzkaller\nenvironment, so I\u0027m taking a guess here. It looks like we\ndo generate correct ETH_HLEN-sized packet, but we redirect\nthe packet to the tunneling device. Before we do so, we\n__skb_pull l2 header and arrive again at skb-\u003elen == 0.\nDoesn\u0027t seem like we can do anything better than having\nan explicit check after __skb_pull?",
  "id": "GHSA-mmcv-ff9h-q89c",
  "modified": "2025-09-15T15:31:22Z",
  "published": "2025-09-15T15:31:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-50253"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/07ec7b502800ba9f7b8b15cb01dd6556bb41aaca"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1b65704b8c08ae92db29f720d3b298031131da53"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5d3f4478d22b2cb1810f6fe0f797411e9d87b3e5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6d935a02658be82585ecb39aab339faa84496650"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/772431f30ca040cfbf31b791d468bac6a9ca74d3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e6a63203e5a90a39392fa1a7ffc60f5e9baf642a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f186303845a01cc7e991f9dc51d7e5a3cdc7aedb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ffbccc5fb0a67424e12f7f8da210c04c8063f797"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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