CVE - CVE-2022-49441

CVE-ID
CVE-2022-49441	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
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---
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/04ee31678c128a6cc7bb057ea189a8624ba5a314 URL:https://git.kernel.org/stable/c/04ee31678c128a6cc7bb057ea189a8624ba5a314 MISC:https://git.kernel.org/stable/c/0bcf44903ef4df742dcada86ccaedd25374ffb50 URL:https://git.kernel.org/stable/c/0bcf44903ef4df742dcada86ccaedd25374ffb50 MISC:https://git.kernel.org/stable/c/18ca0d55e8639b911df8aae1b47598b13f9acded URL:https://git.kernel.org/stable/c/18ca0d55e8639b911df8aae1b47598b13f9acded MISC:https://git.kernel.org/stable/c/3219ac364ac3d8d30771612a6010f1e0b7fa0a28 URL:https://git.kernel.org/stable/c/3219ac364ac3d8d30771612a6010f1e0b7fa0a28 MISC:https://git.kernel.org/stable/c/4af21b12a60ed2d3642284f4f85b42d7dc6ac246 URL:https://git.kernel.org/stable/c/4af21b12a60ed2d3642284f4f85b42d7dc6ac246 MISC:https://git.kernel.org/stable/c/4c253caf9264d2aa47ee806a87986dd8eb91a5d9 URL:https://git.kernel.org/stable/c/4c253caf9264d2aa47ee806a87986dd8eb91a5d9 MISC:https://git.kernel.org/stable/c/6b9dbedbe3499fef862c4dff5217cf91f34e43b3 URL:https://git.kernel.org/stable/c/6b9dbedbe3499fef862c4dff5217cf91f34e43b3 MISC:https://git.kernel.org/stable/c/9834b13e8b962caa28fbcf1f422dd82413da4ede URL:https://git.kernel.org/stable/c/9834b13e8b962caa28fbcf1f422dd82413da4ede MISC:https://git.kernel.org/stable/c/b3c974501d0c32258ae0e04e5cc3fb92383b40f6 URL:https://git.kernel.org/stable/c/b3c974501d0c32258ae0e04e5cc3fb92383b40f6
Assigning CNA
kernel.org
Date Record Created
20250226	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20250226)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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