From 29af35bfbf6caa0d27530150dd0adbf88e3c6eab Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Mon, 22 Jul 2024 11:06:36 +0200 Subject: [PATCH] platform/x86: intel-vbtn: Protect ACPI notify handler against recursion Since commit e2ffcda16290 ("ACPI: OSL: Allow Notify () handlers to run on all CPUs") ACPI notify handlers like the intel-vbtn notify_handler() may run on multiple CPU cores racing with themselves. This race gets hit on Dell Venue 7140 tablets when undocking from the keyboard, causing the handler to try and register priv->switches_dev twice, as can be seen from the dev_info() message getting logged twice: [ 83.861800] intel-vbtn INT33D6:00: Registering Intel Virtual Switches input-dev after receiving a switch event [ 83.861858] input: Intel Virtual Switches as /devices/pci0000:00/0000:00:1f.0/PNP0C09:00/INT33D6:00/input/input17 [ 83.861865] intel-vbtn INT33D6:00: Registering Intel Virtual Switches input-dev after receiving a switch event After which things go seriously wrong: [ 83.861872] sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:1f.0/PNP0C09:00/INT33D6:00/input/input17' ... [ 83.861967] kobject: kobject_add_internal failed for input17 with -EEXIST, don't try to register things with the same name in the same directory. [ 83.877338] BUG: kernel NULL pointer dereference, address: 0000000000000018 ... Protect intel-vbtn notify_handler() from racing with itself with a mutex to fix this. Fixes: e2ffcda16290 ("ACPI: OSL: Allow Notify () handlers to run on all CPUs") Reported-by: En-Wei Wu Closes: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2073001 Signed-off-by: Hans de Goede --- drivers/platform/x86/intel/vbtn.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/drivers/platform/x86/intel/vbtn.c b/drivers/platform/x86/intel/vbtn.c index 9b7ce03ba085..93deda7daac4 100644 --- a/drivers/platform/x86/intel/vbtn.c +++ b/drivers/platform/x86/intel/vbtn.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include #include "../dual_accel_detect.h" @@ -66,6 +67,7 @@ static const struct key_entry intel_vbtn_switchmap[] = { }; struct intel_vbtn_priv { + struct mutex mutex; /* Avoid notify_handler() racing with itself */ struct input_dev *buttons_dev; struct input_dev *switches_dev; bool dual_accel; @@ -155,30 +157,32 @@ static void notify_handler(acpi_handle handle, u32 event, void *context) bool autorelease; int ret; + mutex_lock(&priv->mutex); + if ((ke = sparse_keymap_entry_from_scancode(priv->buttons_dev, event))) { if (!priv->has_buttons) { dev_warn(&device->dev, "Warning: received 0x%02x button event on a device without buttons, please report this.\n", event); - return; + goto out_unlock; } input_dev = priv->buttons_dev; } else if ((ke = sparse_keymap_entry_from_scancode(priv->switches_dev, event))) { if (!priv->has_switches) { /* See dual_accel_detect.h for more info */ if (priv->dual_accel) - return; + goto out_unlock; dev_info(&device->dev, "Registering Intel Virtual Switches input-dev after receiving a switch event\n"); ret = input_register_device(priv->switches_dev); if (ret) - return; + goto out_unlock; priv->has_switches = true; } input_dev = priv->switches_dev; } else { dev_dbg(&device->dev, "unknown event index 0x%x\n", event); - return; + goto out_unlock; } if (priv->wakeup_mode) { @@ -189,7 +193,7 @@ static void notify_handler(acpi_handle handle, u32 event, void *context) * mirroring how the drivers/acpi/button.c code skips this too. */ if (ke->type == KE_KEY) - return; + goto out_unlock; } /* @@ -200,6 +204,9 @@ static void notify_handler(acpi_handle handle, u32 event, void *context) autorelease = val && (!ke_rel || ke_rel->type == KE_IGNORE); sparse_keymap_report_event(input_dev, event, val, autorelease); + +out_unlock: + mutex_unlock(&priv->mutex); } /* @@ -290,6 +297,10 @@ static int intel_vbtn_probe(struct platform_device *device) return -ENOMEM; dev_set_drvdata(&device->dev, priv); + err = devm_mutex_init(&device->dev, &priv->mutex); + if (err) + return err; + priv->dual_accel = dual_accel; priv->has_buttons = has_buttons; priv->has_switches = has_switches; -- 2.45.2