The documentation for `Cursor::peek_next` incorrectly describes it as
"Access the previous node without moving the cursor" when it actually
accesses the next node. Update the description to correctly state
"Access the next node without moving the cursor" to match the function
name and implementation.
Reported-by: Miguel Ojeda <ojeda(a)kernel.org>
Closes: https://github.com/Rust-for-Linux/linux/issues/1205
Fixes: 98c14e40e07a0 ("rust: rbtree: add cursor")
Cc: stable(a)vger.kernel.org
Signed-off-by: WeiKang Guo <guoweikang.kernel(a)outlook.com>
---
rust/kernel/rbtree.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs
index 4729eb56827a..cd187e2ca328 100644
--- a/rust/kernel/rbtree.rs
+++ b/rust/kernel/rbtree.rs
@@ -985,7 +985,7 @@ pub fn peek_prev(&self) -> Option<(&K, &V)> {
self.peek(Direction::Prev)
}
- /// Access the previous node without moving the cursor.
+ /// Access the next node without moving the cursor.
pub fn peek_next(&self) -> Option<(&K, &V)> {
self.peek(Direction::Next)
}
--
2.52.0
The documentation for `Cursor::peek_next` incorrectly describes it as
"Access the previous node without moving the cursor" when it actually
accesses the next node. Update the description to correctly state
"Access the next node without moving the cursor" to match the function
name and implementation.
Reported-by: Miguel Ojeda <ojeda(a)kernel.org>
Closes: https://github.com/Rust-for-Linux/linux/issues/1205
Fixes: 98c14e40e07a0 ("rust: rbtree: add cursor")
Cc: stable(a)vger.kernel.org
Signed-off-by: WeiKang Guo <guoweikang.kernel(a)outlook.com>
---
rust/kernel/rbtree.rs | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs
index 4729eb56827a..cd187e2ca328 100644
--- a/rust/kernel/rbtree.rs
+++ b/rust/kernel/rbtree.rs
@@ -985,7 +985,7 @@ pub fn peek_prev(&self) -> Option<(&K, &V)> {
self.peek(Direction::Prev)
}
- /// Access the previous node without moving the cursor.
+ /// Access the next node without moving the cursor.
pub fn peek_next(&self) -> Option<(&K, &V)> {
self.peek(Direction::Next)
}
--
2.52.0
Before this change the LED was added to leds_list before led_init_core()
gets called adding it the list before led_classdev.set_brightness_work gets
initialized.
This leaves a window where led_trigger_register() of a LED's default
trigger will call led_trigger_set() which calls led_set_brightness()
which in turn will end up queueing the *uninitialized*
led_classdev.set_brightness_work.
This race gets hit by the lenovo-thinkpad-t14s EC driver which registers
2 LEDs with a default trigger provided by snd_ctl_led.ko in quick
succession. The first led_classdev_register() causes an async modprobe of
snd_ctl_led to run and that async modprobe manages to exactly hit
the window where the second LED is on the leds_list without led_init_core()
being called for it, resulting in:
------------[ cut here ]------------
WARNING: CPU: 11 PID: 5608 at kernel/workqueue.c:4234 __flush_work+0x344/0x390
Hardware name: LENOVO 21N2S01F0B/21N2S01F0B, BIOS N42ET93W (2.23 ) 09/01/2025
...
Call trace:
__flush_work+0x344/0x390 (P)
flush_work+0x2c/0x50
led_trigger_set+0x1c8/0x340
led_trigger_register+0x17c/0x1c0
led_trigger_register_simple+0x84/0xe8
snd_ctl_led_init+0x40/0xf88 [snd_ctl_led]
do_one_initcall+0x5c/0x318
do_init_module+0x9c/0x2b8
load_module+0x7e0/0x998
Close the race window by moving the adding of the LED to leds_list to
after the led_init_core() call.
Cc: Sebastian Reichel <sre(a)kernel.org>
Cc: stable(a)vger.kernel.org
Signed-off-by: Hans de Goede <johannes.goede(a)oss.qualcomm.com>
---
Note no Fixes tag as this problem has been around for a long long time,
so I could not really find a good commit for the Fixes tag.
---
drivers/leds/led-class.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index f3faf37f9a08..6b9fa060c3a1 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -560,11 +560,6 @@ int led_classdev_register_ext(struct device *parent,
#ifdef CONFIG_LEDS_BRIGHTNESS_HW_CHANGED
led_cdev->brightness_hw_changed = -1;
#endif
- /* add to the list of leds */
- down_write(&leds_list_lock);
- list_add_tail(&led_cdev->node, &leds_list);
- up_write(&leds_list_lock);
-
if (!led_cdev->max_brightness)
led_cdev->max_brightness = LED_FULL;
@@ -574,6 +569,11 @@ int led_classdev_register_ext(struct device *parent,
led_init_core(led_cdev);
+ /* add to the list of leds */
+ down_write(&leds_list_lock);
+ list_add_tail(&led_cdev->node, &leds_list);
+ up_write(&leds_list_lock);
+
#ifdef CONFIG_LEDS_TRIGGERS
led_trigger_set_default(led_cdev);
#endif
--
2.52.0
lkkbd_interrupt() schedules lk->tq with schedule_work(), and the work
handler lkkbd_reinit() dereferences the lkkbd structure and its
serio/input_dev fields.
lkkbd_disconnect() frees the lkkbd structure without cancelling this
work, so the work can run after the structure has been freed, leading
to a potential use-after-free.
Cancel the pending work in lkkbd_disconnect() before unregistering and
freeing the device, following the same pattern as sunkbd.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Minseong Kim <ii4gsp(a)gmail.com>
Cc: stable(a)vger.kernel.org
Signed-off-by: Minseong Kim <ii4gsp(a)gmail.com>
---
drivers/input/keyboard/lkkbd.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/input/keyboard/lkkbd.c b/drivers/input/keyboard/lkkbd.c
index c035216dd27c..72c477aab1fc 100644
--- a/drivers/input/keyboard/lkkbd.c
+++ b/drivers/input/keyboard/lkkbd.c
@@ -684,6 +684,8 @@ static void lkkbd_disconnect(struct serio *serio)
{
struct lkkbd *lk = serio_get_drvdata(serio);
+ cancel_work_sync(&lk->tq);
+
input_get_device(lk->dev);
input_unregister_device(lk->dev);
serio_close(serio);
--
2.39.5
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 4368a3b96c427ea3299be8cedb28684ba4157529
Gitweb: https://git.kernel.org/tip/4368a3b96c427ea3299be8cedb28684ba4157529
Author: Yazen Ghannam <yazen.ghannam(a)amd.com>
AuthorDate: Tue, 11 Nov 2025 14:53:57
Committer: Ingo Molnar <mingo(a)kernel.org>
CommitterDate: Fri, 12 Dec 2025 09:38:30 +01:00
x86/acpi/boot: Correct acpi_is_processor_usable() check again
ACPI v6.3 defined a new "Online Capable" MADT LAPIC flag. This bit is
used in conjunction with the "Enabled" MADT LAPIC flag to determine if
a CPU can be enabled/hotplugged by the OS after boot.
Before the new bit was defined, the "Enabled" bit was explicitly
described like this (ACPI v6.0 wording provided):
"If zero, this processor is unusable, and the operating system
support will not attempt to use it"
This means that CPU hotplug (based on MADT) is not possible. Many BIOS
implementations follow this guidance. They may include LAPIC entries in
MADT for unavailable CPUs, but since these entries are marked with
"Enabled=0" it is expected that the OS will completely ignore these
entries.
However, QEMU will do the same (include entries with "Enabled=0") for
the purpose of allowing CPU hotplug within the guest.
Comment from QEMU function pc_madt_cpu_entry():
/* ACPI spec says that LAPIC entry for non present
* CPU may be omitted from MADT or it must be marked
* as disabled. However omitting non present CPU from
* MADT breaks hotplug on linux. So possible CPUs
* should be put in MADT but kept disabled.
*/
Recent Linux topology changes broke the QEMU use case. A following fix
for the QEMU use case broke bare metal topology enumeration.
Rework the Linux MADT LAPIC flags check to allow the QEMU use case only
for guests and to maintain the ACPI spec behavior for bare metal.
Remove an unnecessary check added to fix a bare metal case introduced by
the QEMU "fix".
[ bp: Change logic as Michal suggested. ]
Fixes: fed8d8773b8e ("x86/acpi/boot: Correct acpi_is_processor_usable() check")
Fixes: f0551af02130 ("x86/topology: Ignore non-present APIC IDs in a present package")
Closes: https://lore.kernel.org/r/20251024204658.3da9bf3f.michal.pecio@gmail.com
Reported-by: Michal Pecio <michal.pecio(a)gmail.com>
Signed-off-by: Yazen Ghannam <yazen.ghannam(a)amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de>
Signed-off-by: Ingo Molnar <mingo(a)kernel.org>
Tested-by: Michal Pecio <michal.pecio(a)gmail.com>
Tested-by: Ricardo Neri <ricardo.neri-calderon(a)linux.intel.com>
Cc: stable(a)vger.kernel.org
Link: https://lore.kernel.org/20251111145357.4031846-1-yazen.ghannam@amd.com
---
arch/x86/kernel/acpi/boot.c | 12 ++++++++----
arch/x86/kernel/cpu/topology.c | 15 ---------------
2 files changed, 8 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 9fa321a..d6138b2 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -35,6 +35,7 @@
#include <asm/smp.h>
#include <asm/i8259.h>
#include <asm/setup.h>
+#include <asm/hypervisor.h>
#include "sleep.h" /* To include x86_acpi_suspend_lowlevel */
static int __initdata acpi_force = 0;
@@ -164,11 +165,14 @@ static bool __init acpi_is_processor_usable(u32 lapic_flags)
if (lapic_flags & ACPI_MADT_ENABLED)
return true;
- if (!acpi_support_online_capable ||
- (lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
- return true;
+ if (acpi_support_online_capable)
+ return lapic_flags & ACPI_MADT_ONLINE_CAPABLE;
- return false;
+ /*
+ * QEMU expects legacy "Enabled=0" LAPIC entries to be counted as usable
+ * in order to support CPU hotplug in guests.
+ */
+ return !hypervisor_is_type(X86_HYPER_NATIVE);
}
static int __init
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index f55ea3c..23190a7 100644
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -27,7 +27,6 @@
#include <xen/xen.h>
#include <asm/apic.h>
-#include <asm/hypervisor.h>
#include <asm/io_apic.h>
#include <asm/mpspec.h>
#include <asm/msr.h>
@@ -236,20 +235,6 @@ static __init void topo_register_apic(u32 apic_id, u32 acpi_id, bool present)
cpuid_to_apicid[cpu] = apic_id;
topo_set_cpuids(cpu, apic_id, acpi_id);
} else {
- u32 pkgid = topo_apicid(apic_id, TOPO_PKG_DOMAIN);
-
- /*
- * Check for present APICs in the same package when running
- * on bare metal. Allow the bogosity in a guest.
- */
- if (hypervisor_is_type(X86_HYPER_NATIVE) &&
- topo_unit_count(pkgid, TOPO_PKG_DOMAIN, phys_cpu_present_map)) {
- pr_info_once("Ignoring hot-pluggable APIC ID %x in present package.\n",
- apic_id);
- topo_info.nr_rejected_cpus++;
- return;
- }
-
topo_info.nr_disabled_cpus++;
}