FKIE_CVE-2026-98839

Vulnerability from fkie_nvd - Published: 2026-10-18 16:17 - Updated: 2026-10-18 16:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: vt: selection: Fix unsigned underflow and slab-out-of-bounds read in paste_selection() In paste_selection(), the loop copies min_t(unsigned int, vc_sel.buf_len - pasted,tty->receive_room) bytes per iteration into tty_ldisc_receive_buf() and increments pasted += count. Because the selection mutex (vc_sel.lock) is dropped inside the loop Whenever the line discipline buffer fills up and paste_selection() sleeps on tty->write_wait, a concurrent TIOCLINUX (TIOCL_SETSEL) ioctl can replace vc_sel.buffer with a shorter selection and reduce vc_sel.buf_len below pasted. When paste_selection() resumes, vc_sel.buf_len - pasted underflows as an unsigned integer to a large positive value, causing tty_ldisc_receive_buf(ld, vc_sel.buffer + pasted, NULL, count) to read up to 4094 bytes out-of-bounds past the newly allocated vc_sel.buffer. Fix this by terminating the loop when pasted >= vc_sel.buf_len. Kernel stack trace (Linux 7.3.0-rc3): ================================================================== BUG: KASAN: slab-out-of-bounds in n_tty_receive_buf_common+0xa01/0x1650 Read of size 4094 at addr ffff888101c58010 by task kworker/u17:1/65 Workqueue: events_unbound flush_to_ldisc Call Trace: <TASK> dump_stack_lvl+0x70/0xa0 print_report+0x153/0x4c6 kasan_report+0xf1/0x120 kasan_check_range+0x11c/0x200 __asan_memcpy+0x29/0x70 n_tty_receive_buf_common+0xa01/0x1650 tty_ldisc_receive_buf+0x66/0x110 tty_port_default_receive_buf+0x6b/0xb0 flush_to_ldisc+0x1b4/0x410 process_one_work+0x6ff/0x1110 worker_thread+0x4a8/0xb70 kthread+0x307/0x3e0 ret_from_fork+0x3ed/0x680 </TASK> ==================================================================
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/037d7e3ca5c593092f4b0d471eb869a85cbddde0
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/39495ef5d6f8019e62d65807f217a7ca8232727a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/619c6d7dd76fff15a9714fbf02ce299b737f01a2
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/tty/vt/selection.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "037d7e3ca5c593092f4b0d471eb869a85cbddde0",
              "status": "affected",
              "version": "e8c75a30a23c6ba63f4ef6895cbf41fd42f21aa2",
              "versionType": "git"
            },
            {
              "lessThan": "619c6d7dd76fff15a9714fbf02ce299b737f01a2",
              "status": "affected",
              "version": "e8c75a30a23c6ba63f4ef6895cbf41fd42f21aa2",
              "versionType": "git"
            },
            {
              "lessThan": "39495ef5d6f8019e62d65807f217a7ca8232727a",
              "status": "affected",
              "version": "e8c75a30a23c6ba63f4ef6895cbf41fd42f21aa2",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "54c522782fd11a720f959ee9cb5a15bb9580343d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "05c508edc9d0b44e4706d3c2cf14ee12aac210d2",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "e5be0e24ffc7f5783a3864b5b958088ed15be9e8",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "a4719f6d07b2c63223f7452c435c5f578f105cfe",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b4492f1e7456bd162714c0ec2815c2749d930844",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9a9c13ad21a8220cb70c9807a920f43520515f94",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "8c368d36878e2fc99285279fc5e14b3d3cb8947c",
              "versionType": "git"
            },
            {
              "lessThan": "3.17",
              "status": "affected",
              "version": "3.16.83",
              "versionType": "semver"
            },
            {
              "lessThan": "4.5",
              "status": "affected",
              "version": "4.4.216",
              "versionType": "semver"
            },
            {
              "lessThan": "4.10",
              "status": "affected",
              "version": "4.9.216",
              "versionType": "semver"
            },
            {
              "lessThan": "4.15",
              "status": "affected",
              "version": "4.14.173",
              "versionType": "semver"
            },
            {
              "lessThan": "4.20",
              "status": "affected",
              "version": "4.19.109",
              "versionType": "semver"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.25",
              "versionType": "semver"
            },
            {
              "lessThan": "5.6",
              "status": "affected",
              "version": "5.5.9",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/tty/vt/selection.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.6"
            },
            {
              "lessThan": "5.6",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.56",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc6",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvt: selection: Fix unsigned underflow and slab-out-of-bounds read in paste_selection()\n\nIn paste_selection(), the loop copies min_t(unsigned int,\nvc_sel.buf_len - pasted,tty-\u003ereceive_room) bytes per iteration into\ntty_ldisc_receive_buf() and increments pasted += count.\n\nBecause the selection mutex (vc_sel.lock) is dropped inside the loop\nWhenever the line discipline buffer fills up and paste_selection()\nsleeps on tty-\u003ewrite_wait, a concurrent TIOCLINUX (TIOCL_SETSEL) ioctl\ncan replace vc_sel.buffer with a shorter selection and reduce\nvc_sel.buf_len below pasted.\n\nWhen paste_selection() resumes, vc_sel.buf_len - pasted underflows as an\nunsigned integer to a large positive value, causing\ntty_ldisc_receive_buf(ld, vc_sel.buffer + pasted, NULL, count) to read\nup to 4094 bytes out-of-bounds past the newly allocated vc_sel.buffer.\n\nFix this by terminating the loop when pasted \u003e= vc_sel.buf_len.\n\nKernel stack trace (Linux 7.3.0-rc3):\n ==================================================================\n BUG: KASAN: slab-out-of-bounds in n_tty_receive_buf_common+0xa01/0x1650\n Read of size 4094 at addr ffff888101c58010 by task kworker/u17:1/65\n Workqueue: events_unbound flush_to_ldisc\n Call Trace:\n  \u003cTASK\u003e\n  dump_stack_lvl+0x70/0xa0\n  print_report+0x153/0x4c6\n  kasan_report+0xf1/0x120\n  kasan_check_range+0x11c/0x200\n  __asan_memcpy+0x29/0x70\n  n_tty_receive_buf_common+0xa01/0x1650\n  tty_ldisc_receive_buf+0x66/0x110\n  tty_port_default_receive_buf+0x6b/0xb0\n  flush_to_ldisc+0x1b4/0x410\n  process_one_work+0x6ff/0x1110\n  worker_thread+0x4a8/0xb70\n  kthread+0x307/0x3e0\n  ret_from_fork+0x3ed/0x680\n  \u003c/TASK\u003e\n =================================================================="
    }
  ],
  "id": "CVE-2026-98839",
  "lastModified": "2026-10-18T16:17:38.170",
  "metrics": {},
  "published": "2026-10-18T16:17:38.170",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/037d7e3ca5c593092f4b0d471eb869a85cbddde0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/39495ef5d6f8019e62d65807f217a7ca8232727a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/619c6d7dd76fff15a9714fbf02ce299b737f01a2"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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