{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-50073",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2024-50073"
  ],
  "published": "2024-10-29T00:50:48Z",
  "summary": "tty: n_gsm: Fix use-after-free in gsm_cleanup_mux",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntty: n_gsm: Fix use-after-free in gsm_cleanup_mux\n\nBUG: KASAN: slab-use-after-free in gsm_cleanup_mux+0x77b/0x7b0\ndrivers/tty/n_gsm.c:3160 [n_gsm]\nRead of size 8 at addr ffff88815fe99c00 by task poc/3379\nCPU: 0 UID: 0 PID: 3379 Comm: poc Not tainted 6.11.0+ #56\nHardware name: VMware, Inc. VMware Virtual Platform/440BX\nDesktop Reference Platform, BIOS 6.00 11/12/2020\nCall Trace:\n <TASK>\n gsm_cleanup_mux+0x77b/0x7b0 drivers/tty/n_gsm.c:3160 [n_gsm]\n __pfx_gsm_cleanup_mux+0x10/0x10 drivers/tty/n_gsm.c:3124 [n_gsm]\n __pfx_sched_clock_cpu+0x10/0x10 kernel/sched/clock.c:389\n update_load_avg+0x1c1/0x27b0 kernel/sched/fair.c:4500\n __pfx_min_vruntime_cb_rotate+0x10/0x10 kernel/sched/fair.c:846\n __rb_insert_augmented+0x492/0xbf0 lib/rbtree.c:161\n gsmld_ioctl+0x395/0x1450 drivers/tty/n_gsm.c:3408 [n_gsm]\n _raw_spin_lock_irqsave+0x92/0xf0 arch/x86/include/asm/atomic.h:107\n __pfx_gsmld_ioctl+0x10/0x10 drivers/tty/n_gsm.c:3822 [n_gsm]\n ktime_get+0x5e/0x140 kernel/time/timekeeping.c:195\n ldsem_down_read+0x94/0x4e0 arch/x86/include/asm/atomic64_64.h:79\n __pfx_ldsem_down_read+0x10/0x10 drivers/tty/tty_ldsem.c:338\n __pfx_do_vfs_ioctl+0x10/0x10 fs/ioctl.c:805\n tty_ioctl+0x643/0x1100 drivers/tty/tty_io.c:2818\n\nAllocated by task 65:\n gsm_data_alloc.constprop.0+0x27/0x190 drivers/tty/n_gsm.c:926 [n_gsm]\n gsm_send+0x2c/0x580 drivers/tty/n_gsm.c:819 [n_gsm]\n gsm1_receive+0x547/0xad0 drivers/tty/n_gsm.c:3038 [n_gsm]\n gsmld_receive_buf+0x176/0x280 drivers/tty/n_gsm.c:3609 [n_gsm]\n tty_ldisc_receive_buf+0x101/0x1e0 drivers/tty/tty_buffer.c:391\n tty_port_default_receive_buf+0x61/0xa0 drivers/tty/tty_port.c:39\n flush_to_ldisc+0x1b0/0x750 drivers/tty/tty_buffer.c:445\n process_scheduled_works+0x2b0/0x10d0 kernel/workqueue.c:3229\n worker_thread+0x3dc/0x950 kernel/workqueue.c:3391\n kthread+0x2a3/0x370 kernel/kthread.c:389\n ret_from_fork+0x2d/0x70 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:257\n\nFreed by task 3367:\n kfree+0x126/0x420 mm/slub.c:4580\n gsm_cleanup_mux+0x36c/0x7b0 drivers/tty/n_gsm.c:3160 [n_gsm]\n gsmld_ioctl+0x395/0x1450 drivers/tty/n_gsm.c:3408 [n_gsm]\n tty_ioctl+0x643/0x1100 drivers/tty/tty_io.c:2818\n\n[Analysis]\ngsm_msg on the tx_ctrl_list or tx_data_list of gsm_mux\ncan be freed by multi threads through ioctl,which leads\nto the occurrence of uaf. Protect it by gsm tx lock.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.114",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-50073"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/bf171b5e86e41de4c1cf32fb7aefa275c3d7de49"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c29f192e0d44cc1cbaf698fa1ff198f63556691a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0eec592c6a7460ba795d7de29f3dc95cb5422e62"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/9462f4ca56e7d2430fdb6dcc8498244acbfc4489"
    }
  ],
  "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 vulnerability is triggered entirely through local syscalls on a tty file descriptor \u2014 `ioctl(TIOCSETD, N_GSM0710)` followed by concurrent `ioctl(GSMIOC_SETCONF)` on a pty the attacker owns. No network or physical access is involved.\nAC:L - The attacker controls both sides of the race \u2014 two threads issuing `GSMIOC_SETCONF` on the same fd, which `tty_ldisc_ref_wait()`'s read semaphore explicitly permits to run concurrently \u2014 and additionally controls list population by writing to the pty peer to queue `gsm_msg` nodes on demand. No condition depends on attacker-uninfluenceable state.\nPR:L - For mainline v6.0\u2013v6.5 and the never-fixed 5.18.18/5.19.2 stable branches covered by this CVE, `gsmld_open()` has no capability check at all, so any unprivileged local user with a pty reaches the bug; even on kernels carrying the later `capable(CAP_NET_ADMIN)` gate, that is a scoped, non-root-equivalent capability routinely granted to network daemons and containers (`--cap-add=NET_ADMIN`).\nUI:N - The attacker performs every step itself \u2014 allocating the pty, attaching the line discipline, feeding data, and racing the two ioctls. No victim action or cooperating process is required.\nS:U - The corruption and its consequences are confined to the kernel of the running system, a standard local privilege-escalation boundary. No hypervisor, IOMMU, or other security-authority boundary is crossed.\nC:H - The unlocked traversal reads `list.next` from a freed, attacker-reclaimable slab object, and the resulting arbitrary-free primitive converts into a use-after-free on a chosen kernel object, enabling arbitrary kernel memory disclosure.\nI:H - Concurrent `kfree()` of the same nodes double-frees them and corrupts the SLUB freelist, while a sprayed `next` pointer yields `kfree()` of an attacker-chosen address \u2014 an arbitrary-free primitive that is a well-established path to arbitrary write and control-flow hijack.\nA:H - The double-free and use-after-free reliably corrupt slab metadata, producing kernel oops or panic even in unweaponized form, as demonstrated by the KASAN slab-use-after-free report in the fix commit."
    }
  }
}