{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-46771",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2024-46771"
  ],
  "published": "2024-09-18T07:17:19Z",
  "summary": "can: bcm: Remove proc entry when dev is unregistered.",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: bcm: Remove proc entry when dev is unregistered.\n\nsyzkaller reported a warning in bcm_connect() below. [0]\n\nThe repro calls connect() to vxcan1, removes vxcan1, and calls\nconnect() with ifindex == 0.\n\nCalling connect() for a BCM socket allocates a proc entry.\nThen, bcm_sk(sk)->bound is set to 1 to prevent further connect().\n\nHowever, removing the bound device resets bcm_sk(sk)->bound to 0\nin bcm_notify().\n\nThe 2nd connect() tries to allocate a proc entry with the same\nname and sets NULL to bcm_sk(sk)->bcm_proc_read, leaking the\noriginal proc entry.\n\nSince the proc entry is available only for connect()ed sockets,\nlet's clean up the entry when the bound netdev is unregistered.\n\n[0]:\nproc_dir_entry 'can-bcm/2456' already registered\nWARNING: CPU: 1 PID: 394 at fs/proc/generic.c:376 proc_register+0x645/0x8f0 fs/proc/generic.c:375\nModules linked in:\nCPU: 1 PID: 394 Comm: syz-executor403 Not tainted 6.10.0-rc7-g852e42cc2dd4\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\nRIP: 0010:proc_register+0x645/0x8f0 fs/proc/generic.c:375\nCode: 00 00 00 00 00 48 85 ed 0f 85 97 02 00 00 4d 85 f6 0f 85 9f 02 00 00 48 c7 c7 9b cb cf 87 48 89 de 4c 89 fa e8 1c 6f eb fe 90 <0f> 0b 90 90 48 c7 c7 98 37 99 89 e8 cb 7e 22 05 bb 00 00 00 10 48\nRSP: 0018:ffa0000000cd7c30 EFLAGS: 00010246\nRAX: 9e129be1950f0200 RBX: ff1100011b51582c RCX: ff1100011857cd80\nRDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002\nRBP: 0000000000000000 R08: ffd400000000000f R09: ff1100013e78cac0\nR10: ffac800000cd7980 R11: ff1100013e12b1f0 R12: 0000000000000000\nR13: 0000000000000000 R14: 0000000000000000 R15: ff1100011a99a2ec\nFS:  00007fbd7086f740(0000) GS:ff1100013fd00000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00000000200071c0 CR3: 0000000118556004 CR4: 0000000000771ef0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400\nPKRU: 55555554\nCall Trace:\n <TASK>\n proc_create_net_single+0x144/0x210 fs/proc/proc_net.c:220\n bcm_connect+0x472/0x840 net/can/bcm.c:1673\n __sys_connect_file net/socket.c:2049 [inline]\n __sys_connect+0x5d2/0x690 net/socket.c:2066\n __do_sys_connect net/socket.c:2076 [inline]\n __se_sys_connect net/socket.c:2073 [inline]\n __x64_sys_connect+0x8f/0x100 net/socket.c:2073\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xd9/0x1c0 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\nRIP: 0033:0x7fbd708b0e5d\nCode: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 73 9f 1b 00 f7 d8 64 89 01 48\nRSP: 002b:00007fff8cd33f08 EFLAGS: 00000246 ORIG_RAX: 000000000000002a\nRAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fbd708b0e5d\nRDX: 0000000000000010 RSI: 0000000020000040 RDI: 0000000000000003\nRBP: 0000000000000000 R08: 0000000000000040 R09: 0000000000000040\nR10: 0000000000000040 R11: 0000000000000246 R12: 00007fff8cd34098\nR13: 0000000000401280 R14: 0000000000406de8 R15: 00007fbd70ab9000\n </TASK>\nremove_proc_entry: removing non-empty directory 'net/can-bcm', leaking at least '2456'",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
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  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-46771"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/5c680022c4e28ba18ea500f3e29f0428271afa92"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/33ed4ba73caae39f34ab874ba79138badc2c65dd"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/aec92dbebdbec7567d9f56d7c9296a572b8fd849"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/10bfacbd5e8d821011d857bee73310457c9c989a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3b39dc2901aa7a679a5ca981a3de9f8d5658afe8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/4377b79323df62eb5d310354f19b4d130ff58d50"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/abb0a615569ec008e8a93d9f3ab2d5b418ea94d4"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/76fe372ccb81b0c89b6cd2fec26e2f38c958be85"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:52:36Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The entire sequence \u2014 CAN_BCM socket creation, connect(), removal of the bound netdev via RTNL, a second connect(), close(), and reading /proc/net/can-bcm/<ino> \u2014 requires only local syscalls. No remote or adjacent-network input reaches this code.\nAC:L - The attacker performs a deterministic, self-contained sequence (connect \u2192 delete the interface they created \u2192 connect \u2192 close \u2192 read the leaked proc file); there is no race and no condition outside the attacker's control.\nPR:L - An ordinary unprivileged user can open a CAN BCM socket (no capability checks in bcm_connect()) and obtain CAP_NET_ADMIN inside a user namespace (`unshare -Urn`) to create and delete the vcan/vxcan device that triggers bcm_notify(); the leaked proc entry is mode 0644 and world-readable.\nUI:N - The attacker drives every step from a single process; no action by another user or administrator is needed.\nS:U - The dangling proc entry and the freed socket are both kernel objects within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The orphaned procfs entry keeps a pointer to a freed struct sock, so reading it makes bcm_proc_show() dereference and walk lists inside a slab object the attacker can re-allocate with controlled content, yielding an attacker-influenced kernel memory read returned to userspace (plus %pK pointer disclosure).\nI:H - The dangling reference is a use-after-free on a freed socket whose slab can be sprayed with attacker-controlled data; the resulting corrupted-object dereferences and list traversals are the standard basis for control-flow/heap manipulation primitives.\nA:H - The second connect() triggers a proc_register() WARN (fatal with panic_on_warn), and any later read of the leaked entry dereferences freed memory, causing an oops or an endless loop over corrupted list pointers, plus permanent procfs/netns resource leakage."
    }
  }
}