From: Jakub Lewalski <jakub.lewalski@nokia.com> stable inclusion from stable-v6.6.96 commit 8e958d10dd0ce5ae674cce460db5c9ca3f25243b category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICL7YU CVE: CVE-2025-38262 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 6bd697b5fc39fd24e2aa418c7b7d14469f550a93 ] When two instances of uart devices are probing, a concurrency race can occur. If one thread calls uart_register_driver function, which first allocates and assigns memory to 'uart_state' member of uart_driver structure, the other instance can bypass uart driver registration and call ulite_assign. This calls uart_add_one_port, which expects the uart driver to be fully initialized. This leads to a kernel panic due to a null pointer dereference: [ 8.143581] BUG: kernel NULL pointer dereference, address: 00000000000002b8 [ 8.156982] #PF: supervisor write access in kernel mode [ 8.156984] #PF: error_code(0x0002) - not-present page [ 8.156986] PGD 0 P4D 0 ... [ 8.180668] RIP: 0010:mutex_lock+0x19/0x30 [ 8.188624] Call Trace: [ 8.188629] ? __die_body.cold+0x1a/0x1f [ 8.195260] ? page_fault_oops+0x15c/0x290 [ 8.209183] ? __irq_resolve_mapping+0x47/0x80 [ 8.209187] ? exc_page_fault+0x64/0x140 [ 8.209190] ? asm_exc_page_fault+0x22/0x30 [ 8.209196] ? mutex_lock+0x19/0x30 [ 8.223116] uart_add_one_port+0x60/0x440 [ 8.223122] ? proc_tty_register_driver+0x43/0x50 [ 8.223126] ? tty_register_driver+0x1ca/0x1e0 [ 8.246250] ulite_probe+0x357/0x4b0 [uartlite] To prevent it, move uart driver registration in to init function. This will ensure that uart_driver is always registered when probe function is called. Signed-off-by: Jakub Lewalski <jakub.lewalski@nokia.com> Signed-off-by: Elodie Decerle <elodie.decerle@nokia.com> Link: https://lore.kernel.org/r/20250331160732.2042-1-elodie.decerle@nokia.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yi Yang <yiyang13@huawei.com> --- drivers/tty/serial/uartlite.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c index b225a78f6175..9f39bafa7fa9 100644 --- a/drivers/tty/serial/uartlite.c +++ b/drivers/tty/serial/uartlite.c @@ -872,16 +872,6 @@ static int ulite_probe(struct platform_device *pdev) pm_runtime_set_active(&pdev->dev); pm_runtime_enable(&pdev->dev); - if (!ulite_uart_driver.state) { - dev_dbg(&pdev->dev, "uartlite: calling uart_register_driver()\n"); - ret = uart_register_driver(&ulite_uart_driver); - if (ret < 0) { - dev_err(&pdev->dev, "Failed to register driver\n"); - clk_disable_unprepare(pdata->clk); - return ret; - } - } - ret = ulite_assign(&pdev->dev, id, res->start, irq, pdata); pm_runtime_mark_last_busy(&pdev->dev); @@ -922,16 +912,25 @@ static struct platform_driver ulite_platform_driver = { static int __init ulite_init(void) { + int ret; + + pr_debug("uartlite: calling uart_register_driver()\n"); + ret = uart_register_driver(&ulite_uart_driver); + if (ret) + return ret; pr_debug("uartlite: calling platform_driver_register()\n"); - return platform_driver_register(&ulite_platform_driver); + ret = platform_driver_register(&ulite_platform_driver); + if (ret) + uart_unregister_driver(&ulite_uart_driver); + + return ret; } static void __exit ulite_exit(void) { platform_driver_unregister(&ulite_platform_driver); - if (ulite_uart_driver.state) - uart_unregister_driver(&ulite_uart_driver); + uart_unregister_driver(&ulite_uart_driver); } module_init(ulite_init); -- 2.25.1