ksmbd: fix use-after-free of share_conf in compound request_CVE-2026-23428

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free of share_conf in compound request\n\nsmb2_get_ksmbd_tcon() reuses work->tcon in compound requests without\nvalidating tcon->t_state. ksmbd_tree_conn_lookup() checks t_state ==\nTREE_CONNECTED on the initial lookup path, but the compound reuse path\nbypasses this check entirely.\n\nIf a prior command in the compound (SMB2_TREE_DISCONNECT) sets t_state\nto TREE_DISCONNECTED and frees share_conf via ksmbd_share_config_put(),\nsubsequent commands dereference the freed share_conf through\nwork->tcon->share_conf.\n\nKASAN report:\n\n[    4.144653] ==================================================================\n[    4.145059] BUG: KASAN: slab-use-after-free in smb2_write+0xc74/0xe70\n[    4.145415] Read of size 4 at addr ffff88810430c194 by task kworker/1:1/44\n[    4.145772]\n[    4.145867] CPU: 1 UID: 0 PID: 44 Comm: kworker/1:1 Not tainted 7.0.0-rc3+ #60 PREEMPTLAZY\n[    4.145871] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n[    4.145875] Workqueue: ksmbd-io handle_ksmbd_work\n[    4.145888] Call Trace:\n[    4.145892]  <TASK>\n[    4.145894]  dump_stack_lvl+0x64/0x80\n[    4.145910]  print_report+0xce/0x660\n[    4.145919]  ? __pfx__raw_spin_lock_irqsave+0x10/0x10\n[    4.145928]  ? smb2_write+0xc74/0xe70\n[    4.145931]  kasan_report+0xce/0x100\n[    4.145934]  ? smb2_write+0xc74/0xe70\n[    4.145937]  smb2_write+0xc74/0xe70\n[    4.145939]  ? __pfx_smb2_write+0x10/0x10\n[    4.145942]  ? _raw_spin_unlock+0xe/0x30\n[    4.145945]  ? ksmbd_smb2_check_message+0xeb2/0x24c0\n[    4.145948]  ? smb2_tree_disconnect+0x31c/0x480\n[    4.145951]  handle_ksmbd_work+0x40f/0x1080\n[    4.145953]  process_one_work+0x5fa/0xef0\n[    4.145962]  ? assign_work+0x122/0x3e0\n[    4.145964]  worker_thread+0x54b/0xf70\n[    4.145967]  ? __pfx_worker_thread+0x10/0x10\n[    4.145970]  kthread+0x346/0x470\n[    4.145976]  ? recalc_sigpending+0x19b/0x230\n[    4.145980]  ? __pfx_kthread+0x10/0x10\n[    4.145984]  ret_from_fork+0x4fb/0x6c0\n[    4.145992]  ? __pfx_ret_from_fork+0x10/0x10\n[    4.145995]  ? __switch_to+0x36c/0xbe0\n[    4.145999]  ? __pfx_kthread+0x10/0x10\n[    4.146003]  ret_from_fork_asm+0x1a/0x30\n[    4.146013]  </TASK>\n[    4.146014]\n[    4.149858] Allocated by task 44:\n[    4.149953]  kasan_save_stack+0x33/0x60\n[    4.150061]  kasan_save_track+0x14/0x30\n[    4.150169]  __kasan_kmalloc+0x8f/0xa0\n[    4.150274]  ksmbd_share_config_get+0x1dd/0xdd0\n[    4.150401]  ksmbd_tree_conn_connect+0x7e/0x600\n[    4.150529]  smb2_tree_connect+0x2e6/0x1000\n[    4.150645]  handle_ksmbd_work+0x40f/0x1080\n[    4.150761]  process_one_work+0x5fa/0xef0\n[    4.150873]  worker_thread+0x54b/0xf70\n[    4.150978]  kthread+0x346/0x470\n[    4.151071]  ret_from_fork+0x4fb/0x6c0\n[    4.151176]  ret_from_fork_asm+0x1a/0x30\n[    4.151286]\n[    4.151332] Freed by task 44:\n[    4.151418]  kasan_save_stack+0x33/0x60\n[    4.151526]  kasan_save_track+0x14/0x30\n[    4.151634]  kasan_save_free_info+0x3b/0x60\n[    4.151751]  __kasan_slab_free+0x43/0x70\n[    4.151861]  kfree+0x1ca/0x430\n[    4.151952]  __ksmbd_tree_conn_disconnect+0xc8/0x190\n[    4.152088]  smb2_tree_disconnect+0x1cd/0x480\n[    4.152211]  handle_ksmbd_work+0x40f/0x1080\n[    4.152326]  process_one_work+0x5fa/0xef0\n[    4.152438]  worker_thread+0x54b/0xf70\n[    4.152545]  kthread+0x346/0x470\n[    4.152638]  ret_from_fork+0x4fb/0x6c0\n[    4.152743]  ret_from_fork_asm+0x1a/0x30\n[    4.152853]\n[    4.152900] The buggy address belongs to the object at ffff88810430c180\n[    4.152900]  which belongs to the cache kmalloc-96 of size 96\n[    4.153226] The buggy address is located 20 bytes inside of\n[    4.153226]  freed 96-byte region [ffff88810430c180, ffff88810430c1e0)\n[    4.153549]\n[    4.153596] The buggy address belongs to the physical page:\n[    4.153750] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88810430ce80 pfn:0x10430c\n[    4.154000] flags: 0x\n---truncated---",
    "published": "2026-04-03T15:15:14.981Z",
    "modified": "2026-04-27T14:02:19.319Z",
    "type": "cve",
    "title": "ksmbd: fix use-after-free of share_conf in compound request",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/d08417981155883068b7260d9500ca306a03edac\nhttps://git.kernel.org/stable/c/eae0dc86f71e6f3294c0cd7ffc05039258d243af\nhttps://git.kernel.org/stable/c/806f13752652216db0c309392b4db3e64eeed4f2\nhttps://git.kernel.org/stable/c/c742b46a153d3ff95ff0825ab1950c87b9e14470\nhttps://git.kernel.org/stable/c/7f7468fd2a7554cea91b7d430335a3dbf01dcc09\nhttps://git.kernel.org/stable/c/a5929c2020ce54e1dcbd1078c0f30b8aaf73c105\nhttps://git.kernel.org/stable/c/c33615f995aee80657b9fdfbc4ee7f49c2bd733d",
    "id": "CVE-2026-23428",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "Linux Linux eb947403518ea3d93f6d89264bb1f5416bb0c7d0\nLinux Linux 854156d12caa9d36de1cf5f084591c7686cc8a9d\nLinux Linux 5005bcb4219156f1bf7587b185080ec1da08518e\nLinux Linux 5005bcb4219156f1bf7587b185080ec1da08518e\nLinux Linux 5005bcb4219156f1bf7587b185080ec1da08518e\nLinux Linux 5005bcb4219156f1bf7587b185080ec1da08518e\nLinux Linux 5005bcb4219156f1bf7587b185080ec1da08518e\nLinux Linux d1066c1b3663401cd23c0d6e60cdae750ce00c0f\nLinux Linux 6.4",
    "sourceHref": "",
    "cvss": {
        "score": 9.8,
        "severity": "CRITICAL",
        "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Linux",
    "version": "eb947403518ea3d93f6d89264bb1f5416bb0c7d0",
    "vendor": "Linux",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}