fkie_cve-2022-49441
Vulnerability from fkie_nvd
Published
2025-02-26 07:01
Modified
2025-03-17 16:53
Summary
In the Linux kernel, the following vulnerability has been resolved: tty: fix deadlock caused by calling printk() under tty_port->lock pty_write() invokes kmalloc() which may invoke a normal printk() to print failure message. This can cause a deadlock in the scenario reported by syz-bot below: CPU0 CPU1 CPU2 ---- ---- ---- lock(console_owner); lock(&port_lock_key); lock(&port->lock); lock(&port_lock_key); lock(&port->lock); lock(console_owner); As commit dbdda842fe96 ("printk: Add console owner and waiter logic to load balance console writes") said, such deadlock can be prevented by using printk_deferred() in kmalloc() (which is invoked in the section guarded by the port->lock). But there are too many printk() on the kmalloc() path, and kmalloc() can be called from anywhere, so changing printk() to printk_deferred() is too complicated and inelegant. Therefore, this patch chooses to specify __GFP_NOWARN to kmalloc(), so that printk() will not be called, and this deadlock problem can be avoided. Syzbot reported the following lockdep error: ====================================================== WARNING: possible circular locking dependency detected 5.4.143-00237-g08ccc19a-dirty #10 Not tainted ------------------------------------------------------ syz-executor.4/29420 is trying to acquire lock: ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1752 [inline] ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: vprintk_emit+0x2ca/0x470 kernel/printk/printk.c:2023 but task is already holding lock: ffff8880119c9158 (&port->lock){-.-.}-{2:2}, at: pty_write+0xf4/0x1f0 drivers/tty/pty.c:120 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&port->lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 tty_port_tty_get drivers/tty/tty_port.c:288 [inline] <-- lock(&port->lock); tty_port_default_wakeup+0x1d/0xb0 drivers/tty/tty_port.c:47 serial8250_tx_chars+0x530/0xa80 drivers/tty/serial/8250/8250_port.c:1767 serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1854 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1827 [inline] <-- lock(&port_lock_key); serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1870 serial8250_interrupt+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x109/0xa50 kernel/irq/handle.c:156 [...] -> #1 (&port_lock_key){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 serial8250_console_write+0x184/0xa40 drivers/tty/serial/8250/8250_port.c:3198 <-- lock(&port_lock_key); call_console_drivers kernel/printk/printk.c:1819 [inline] console_unlock+0x8cb/0xd00 kernel/printk/printk.c:2504 vprintk_emit+0x1b5/0x470 kernel/printk/printk.c:2024 <-- lock(console_owner); vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394 printk+0xba/0xed kernel/printk/printk.c:2084 register_console+0x8b3/0xc10 kernel/printk/printk.c:2829 univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:681 console_init+0x49d/0x6d3 kernel/printk/printk.c:2915 start_kernel+0x5e9/0x879 init/main.c:713 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 -> #0 (console_owner){....}-{0:0}: [...] lock_acquire+0x127/0x340 kernel/locking/lockdep.c:4734 console_trylock_spinning kernel/printk/printk.c:1773 ---truncated---



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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntty: fix deadlock caused by calling printk() under tty_port-\u003elock\n\npty_write() invokes kmalloc() which may invoke a normal printk() to print\nfailure message.  This can cause a deadlock in the scenario reported by\nsyz-bot below:\n\n       CPU0              CPU1                    CPU2\n       ----              ----                    ----\n                         lock(console_owner);\n                                                 lock(\u0026port_lock_key);\n  lock(\u0026port-\u003elock);\n                         lock(\u0026port_lock_key);\n                                                 lock(\u0026port-\u003elock);\n  lock(console_owner);\n\nAs commit dbdda842fe96 (\"printk: Add console owner and waiter logic to\nload balance console writes\") said, such deadlock can be prevented by\nusing printk_deferred() in kmalloc() (which is invoked in the section\nguarded by the port-\u003elock).  But there are too many printk() on the\nkmalloc() path, and kmalloc() can be called from anywhere, so changing\nprintk() to printk_deferred() is too complicated and inelegant.\n\nTherefore, this patch chooses to specify __GFP_NOWARN to kmalloc(), so\nthat printk() will not be called, and this deadlock problem can be\navoided.\n\nSyzbot reported the following lockdep error:\n\n======================================================\nWARNING: possible circular locking dependency detected\n5.4.143-00237-g08ccc19a-dirty #10 Not tainted\n------------------------------------------------------\nsyz-executor.4/29420 is trying to acquire lock:\nffffffff8aedb2a0 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1752 [inline]\nffffffff8aedb2a0 (console_owner){....}-{0:0}, at: vprintk_emit+0x2ca/0x470 kernel/printk/printk.c:2023\n\nbut task is already holding lock:\nffff8880119c9158 (\u0026port-\u003elock){-.-.}-{2:2}, at: pty_write+0xf4/0x1f0 drivers/tty/pty.c:120\n\nwhich lock already depends on the new lock.\n\nthe existing dependency chain (in reverse order) is:\n\n-\u003e #2 (\u0026port-\u003elock){-.-.}-{2:2}:\n       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]\n       _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159\n       tty_port_tty_get drivers/tty/tty_port.c:288 [inline]          \t\t\u003c-- lock(\u0026port-\u003elock);\n       tty_port_default_wakeup+0x1d/0xb0 drivers/tty/tty_port.c:47\n       serial8250_tx_chars+0x530/0xa80 drivers/tty/serial/8250/8250_port.c:1767\n       serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1854\n       serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1827 [inline] \t\u003c-- lock(\u0026port_lock_key);\n       serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1870\n       serial8250_interrupt+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126\n       __handle_irq_event_percpu+0x109/0xa50 kernel/irq/handle.c:156\n       [...]\n\n-\u003e #1 (\u0026port_lock_key){-.-.}-{2:2}:\n       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]\n       _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159\n       serial8250_console_write+0x184/0xa40 drivers/tty/serial/8250/8250_port.c:3198\n\t\t\t\t\t\t\t\t\t\t\u003c-- lock(\u0026port_lock_key);\n       call_console_drivers kernel/printk/printk.c:1819 [inline]\n       console_unlock+0x8cb/0xd00 kernel/printk/printk.c:2504\n       vprintk_emit+0x1b5/0x470 kernel/printk/printk.c:2024\t\t\t\u003c-- lock(console_owner);\n       vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394\n       printk+0xba/0xed kernel/printk/printk.c:2084\n       register_console+0x8b3/0xc10 kernel/printk/printk.c:2829\n       univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:681\n       console_init+0x49d/0x6d3 kernel/printk/printk.c:2915\n       start_kernel+0x5e9/0x879 init/main.c:713\n       secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241\n\n-\u003e #0 (console_owner){....}-{0:0}:\n       [...]\n       lock_acquire+0x127/0x340 kernel/locking/lockdep.c:4734\n       console_trylock_spinning kernel/printk/printk.c:1773 \n---truncated---"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: tty: se corrige el bloqueo causado por llamar a printk() bajo tty_port-\u0026gt;lock pty_write() invoca kmalloc() que puede invocar un printk() normal para imprimir un mensaje de error. Esto puede causar un bloqueo en el escenario informado por syz-bot a continuaci\u00f3n: CPU0 CPU1 CPU2 ---- ---- ---- lock(console_owner); lock(\u0026amp;port_lock_key); lock(\u0026amp;port-\u0026gt;lock); lock(\u0026amp;port_lock_key); lock(\u0026amp;port-\u0026gt;lock); lock(console_owner); Como dijo el commit dbdda842fe96 (\"printk: Agregar l\u00f3gica de propietario y espera de consola para equilibrar la carga de escrituras de consola\"), dicho bloqueo se puede prevenir usando printk_deferred() en kmalloc() (que se invoca en la secci\u00f3n protegida por port-\u0026gt;lock). Pero hay demasiados printk() en la ruta kmalloc() y kmalloc() se puede llamar desde cualquier lugar, por lo que cambiar printk() a printk_deferred() es demasiado complicado y poco elegante. Por lo tanto, este parche elige especificar __GFP_NOWARN en kmalloc(), de modo que no se llame a printk() y se pueda evitar este problema de bloqueo. Syzbot inform\u00f3 el siguiente error de lockdep: ======================================================== ADVERTENCIA: posible dependencia de bloqueo circular detectada 5.4.143-00237-g08ccc19a-dirty #10 Not tainted ------------------------------------------------------ syz-executor.4/29420 is trying to acquire lock: ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:1752 [inline] ffffffff8aedb2a0 (console_owner){....}-{0:0}, at: vprintk_emit+0x2ca/0x470 kernel/printk/printk.c:2023 but task is already holding lock: ffff8880119c9158 (\u0026amp;port-\u0026gt;lock){-.-.}-{2:2}, at: pty_write+0xf4/0x1f0 drivers/tty/pty.c:120 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -\u0026gt; #2 (\u0026amp;port-\u0026gt;lock){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 tty_port_tty_get drivers/tty/tty_port.c:288 [inline] \u0026lt;-- lock(\u0026amp;port-\u0026gt;lock); tty_port_default_wakeup+0x1d/0xb0 drivers/tty/tty_port.c:47 serial8250_tx_chars+0x530/0xa80 drivers/tty/serial/8250/8250_port.c:1767 serial8250_handle_irq.part.0+0x31f/0x3d0 drivers/tty/serial/8250/8250_port.c:1854 serial8250_handle_irq drivers/tty/serial/8250/8250_port.c:1827 [inline] \u0026lt;-- lock(\u0026amp;port_lock_key); serial8250_default_handle_irq+0xb2/0x220 drivers/tty/serial/8250/8250_port.c:1870 serial8250_interrupt+0xfd/0x200 drivers/tty/serial/8250/8250_core.c:126 __handle_irq_event_percpu+0x109/0xa50 kernel/irq/handle.c:156 [...] -\u0026gt; #1 (\u0026amp;port_lock_key){-.-.}-{2:2}: __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x35/0x50 kernel/locking/spinlock.c:159 serial8250_console_write+0x184/0xa40 drivers/tty/serial/8250/8250_port.c:3198 \u0026lt;-- lock(\u0026amp;port_lock_key); call_console_drivers kernel/printk/printk.c:1819 [inline] console_unlock+0x8cb/0xd00 kernel/printk/printk.c:2504 vprintk_emit+0x1b5/0x470 kernel/printk/printk.c:2024 \u0026lt;-- lock(console_owner); vprintk_func+0x8d/0x250 kernel/printk/printk_safe.c:394 printk+0xba/0xed kernel/printk/printk.c:2084 register_console+0x8b3/0xc10 kernel/printk/printk.c:2829 univ8250_console_init+0x3a/0x46 drivers/tty/serial/8250/8250_core.c:681 console_init+0x49d/0x6d3 kernel/printk/printk.c:2915 start_kernel+0x5e9/0x879 init/main.c:713 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241 -\u0026gt; #0 (console_owner){....}-{0:0}: [...] lock_acquire+0x127/0x340 kernel/locking/lockdep.c:4734 console_trylock_spinning kernel/printk/printk.c:1773 ---truncated--- "
    }
  ],
  "id": "CVE-2022-49441",
  "lastModified": "2025-03-17T16:53:58.013",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2025-02-26T07:01:20.523",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/04ee31678c128a6cc7bb057ea189a8624ba5a314"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/0bcf44903ef4df742dcada86ccaedd25374ffb50"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/18ca0d55e8639b911df8aae1b47598b13f9acded"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/3219ac364ac3d8d30771612a6010f1e0b7fa0a28"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/4af21b12a60ed2d3642284f4f85b42d7dc6ac246"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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      "url": "https://git.kernel.org/stable/c/4c253caf9264d2aa47ee806a87986dd8eb91a5d9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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      "url": "https://git.kernel.org/stable/c/6b9dbedbe3499fef862c4dff5217cf91f34e43b3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/9834b13e8b962caa28fbcf1f422dd82413da4ede"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/b3c974501d0c32258ae0e04e5cc3fb92383b40f6"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-667"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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