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        "ecosystem": "Linux",
        "name": "Kernel"
      },
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          "type": "ECOSYSTEM"
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  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45842.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nslip: reject VJ receive packets on instances with no rstate array\n\nslhc_init() accepts rslots == 0 as a valid configuration, with the\ndocumented meaning of 'no receive compression'. In that case the\nallocation loop in slhc_init() is skipped, so comp-\u003erstate stays\nNULL and comp-\u003erslot_limit stays 0 (from the kzalloc of struct\nslcompress).\n\nThe receive helpers do not defend against that configuration.\nslhc_uncompress() dereferences comp-\u003erstate[x] when the VJ header\ncarries an explicit connection ID, and slhc_remember() later assigns\ncs = \u0026comp-\u003erstate[...] after only comparing the packet's slot number\nto comp-\u003erslot_limit. Because rslot_limit is 0, slot 0 passes the\nrange check, and the code dereferences a NULL rstate.\n\nThe configuration is reachable in-tree through PPP. PPPIOCSMAXCID\nstores its argument in a signed int, and (val \u003e\u003e 16) uses arithmetic\nshift. Passing 0xffff0000 therefore sign-extends to -1, so val2 + 1\nis 0 and ppp_generic.c ends up calling slhc_init(0, 1). Because\n/dev/ppp open is gated by ns_capable(CAP_NET_ADMIN), the whole path\nis reachable from an unprivileged user namespace. Once the malformed\nVJ state is installed, any inbound VJ-compressed or VJ-uncompressed\nframe that selects slot 0 crashes the kernel in softirq context:\n\n Oops: general protection fault, probably for non-canonical\n       address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]\n RIP: 0010:slhc_uncompress (drivers/net/slip/slhc.c:519)\n Call Trace:\n  \u003cTASK\u003e\n  ppp_receive_nonmp_frame (drivers/net/ppp/ppp_generic.c:2466)\n  ppp_input (drivers/net/ppp/ppp_generic.c:2359)\n  ppp_async_process (drivers/net/ppp/ppp_async.c:492)\n  tasklet_action_common (kernel/softirq.c:926)\n  handle_softirqs (kernel/softirq.c:623)\n  run_ksoftirqd (kernel/softirq.c:1055)\n  smpboot_thread_fn (kernel/smpboot.c:160)\n  kthread (kernel/kthread.c:436)\n  ret_from_fork (arch/x86/kernel/process.c:164)\n  \u003c/TASK\u003e\n\nReject the receive side on such instances instead of touching rstate.\nslhc_uncompress() falls through to its existing 'bad' label, which\nbumps sls_i_error and enters the toss state. slhc_remember() mirrors\nthat with an explicit sls_i_error increment followed by slhc_toss();\nthe sls_i_runt counter is not used here because a missing rstate is\nan internal configuration state, not a runt packet.\n\nThe transmit path is unaffected: the only in-tree caller that picks\nrslots from userspace (ppp_generic.c) still supplies tslots \u003e= 1, and\nslip.c always calls slhc_init(16, 16), so comp-\u003etstate remains valid\nand slhc_compress() continues to work.",
  "id": "CVE-2026-45842",
  "modified": "2026-07-08T05:38:12.483934130Z",
  "published": "2026-05-27T09:24:42.637Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3d71c961febddd855d3ae9a519eeb96c8023f430"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4aa9eca6fda2919027dfd7a7cc69334982d89586"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/72304fec672e8aac9ee7b9c475db96b37cca8d8d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7b0d9e878ec2b21d99ae8051b3dda59cdb66c152"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9e1ff0eead073c4f46d874ad2526b7dda5465faf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c6980e8b1a86288167f34966fa5219031999b6f1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de42f86e2cf5028a97e74c25869d1a962b13c301"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e76607442d5b73e1ba6768f501ef815bb58c2c0e"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45842.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45842"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "summary": "slip: reject VJ receive packets on instances with no rstate array"
}