CVE-2026-74686

In the Linux kernel, the following vulnerability has been resolved:

rqspinlock: Reset tail when preserving queue on deadlock

Currently, the destruction of the waiter queue is suppressed for rqspinlock in cases where a deadlock is detected. Deadlock checks happen relatively frequently (on entry for AA, within 1ms for ABBA), and waiter threads may not be involved in locking scenarios involving deadlocks. Thus, it is useful to not flush the queue and let other waiters take a stab at acquiring the lock after we detect a deadlock and exit.

However, we need to follow the same logic as what we did previously for the waitq_timeout label: reset the tail, and if we cannot, signal the next waiter appropriately. In case of deadlocks, this signal would just mark the MCS node as unlocked, and in case of timeouts, it would signal RES_TIMEOUT_VAL. The difference thus is in the value propagated, which decides whether the queue remains active or gets flushed.

Not doing the tail reset, and waiting for the next waiter can lead to cases where we are the final waiter, and thus no next waiter arrives, leading to intermittent stalls in this path. Once the next waiter does join, we will be unblocked. In the theoretical case when the next waiter never joins, we risk stalling indefinitely.

This can only happen for ABBA deadlocks, since entry into the wait queue is guarded with AA checks. A precise sequence of executions leading up to this scenario can be:

CPU 0 holds lock A. CPU 1 holds lock B. CPU 2 attempts lock B, becomes the pending waiter for B. CPU 0 attempts lock B. B has locked+pending bits set, thus CPU 0 queues. CPU 1 attempts lock A. CPU 0 detects an ABBA deadlock.

Once deadlock detection happens for CPU 0, it will sit waiting for the next waiter in the queue to populate node->next, which will experience delays until such a waiter arrives.

Fix this by adjusting the logic for the check for deadlocks preceding the waitq_timeout label. It would make sense to consolidate code for both cases and use 'ret' to distinguish the value being propagated, but that is left as an exercise for a future refactoring task to avoid diff noise in this patch.

In the Linux kernel, the following vulnerability has been resolved:

rqspinlock: Reset tail when preserving queue on deadlock

Currently, the destruction of the waiter queue is suppressed for rqspinlock in cases where a deadlock is detected. Deadlock checks happen relatively frequently (on entry for AA, within 1ms for ABBA), and waiter threads may not be involved in locking scenarios involving deadlocks. Thus, it is useful to not flush the queue and let other waiters take a stab at acquiring the lock after we detect a deadlock and exit.

However, we need to follow the same logic as what we did previously for the waitq_timeout label: reset the tail, and if we cannot, signal the next waiter appropriately. In case of deadlocks, this signal would just mark the MCS node as unlocked, and in case of timeouts, it would signal RES_TIMEOUT_VAL. The difference thus is in the value propagated, which decides whether the queue remains active or gets flushed.

Not doing the tail reset, and waiting for the next waiter can lead to cases where we are the final waiter, and thus no next waiter arrives, leading to intermittent stalls in this path. Once the next waiter does join, we will be unblocked. In the theoretical case when the next waiter never joins, we risk stalling indefinitely.

This can only happen for ABBA deadlocks, since entry into the wait queue is guarded with AA checks. A precise sequence of executions leading up to this scenario can be:

CPU 0 holds lock A. CPU 1 holds lock B. CPU 2 attempts lock B, becomes the pending waiter for B. CPU 0 attempts lock B. B has locked+pending bits set, thus CPU 0 queues. CPU 1 attempts lock A. CPU 0 detects an ABBA deadlock.

Once deadlock detection happens for CPU 0, it will sit waiting for the next waiter in the queue to populate node->next, which will experience delays until such a waiter arrives.

Fix this by adjusting the logic for the check for deadlocks preceding the waitq_timeout label. It would make sense to consolidate code for both cases and use 'ret' to distinguish the value being propagated, but that is left as an exercise for a future refactoring task to avoid diff noise in this patch.

In the Linux kernel, the following vulnerability has been resolved:

rqspinlock: Reset tail when preserving queue on deadlock

Currently, the destruction of the waiter queue is suppressed for rqspinlock in cases where a deadlock is detected. Deadlock checks happen relatively frequently (on entry for AA, within 1ms for ABBA), and waiter threads may not be involved in locking scenarios involving deadlocks. Thus, it is useful to not flush the queue and let other waiters take a stab at acquiring the lock after we detect a deadlock and exit.

However, we need to follow the same logic as what we did previously for the waitq_timeout label: reset the tail, and if we cannot, signal the next waiter appropriately. In case of deadlocks, this signal would just mark the MCS node as unlocked, and in case of timeouts, it would signal RES_TIMEOUT_VAL. The difference thus is in the value propagated, which decides whether the queue remains active or gets flushed.

Not doing the tail reset, and waiting for the next waiter can lead to cases where we are the final waiter, and thus no next waiter arrives, leading to intermittent stalls in this path. Once the next waiter does join, we will be unblocked. In the theoretical case when the next waiter never joins, we risk stalling indefinitely.

This can only happen for ABBA deadlocks, since entry into the wait queue is guarded with AA checks. A precise sequence of executions leading up to this scenario can be:

CPU 0 holds lock A. CPU 1 holds lock B. CPU 2 attempts lock B, becomes the pending waiter for B. CPU 0 attempts lock B. B has locked+pending bits set, thus CPU 0 queues. CPU 1 attempts lock A. CPU 0 detects an ABBA deadlock.

Once deadlock detection happens for CPU 0, it will sit waiting for the next waiter in the queue to populate node->next, which will experience delays until such a waiter arrives.

Fix this by adjusting the logic for the check for deadlocks preceding the waitq_timeout label. It would make sense to consolidate code for both cases and use 'ret' to distinguish the value being propagated, but that is left as an exercise for a future refactoring task to avoid diff noise in this patch.

In the Linux kernel, the following vulnerability has been resolved:

rqspinlock: Reset tail when preserving queue on deadlock

Currently, the destruction of the waiter queue is suppressed for rqspinlock in cases where a deadlock is detected. Deadlock checks happen relatively frequently (on entry for AA, within 1ms for ABBA), and waiter threads may not be involved in locking scenarios involving deadlocks. Thus, it is useful to not flush the queue and let other waiters take a stab at acquiring the lock after we detect a deadlock and exit.

However, we need to follow the same logic as what we did previously for the waitq_timeout label: reset the tail, and if we cannot, signal the next waiter appropriately. In case of deadlocks, this signal would just mark the MCS node as unlocked, and in case of timeouts, it would signal RES_TIMEOUT_VAL. The difference thus is in the value propagated, which decides whether the queue remains active or gets flushed.

Not doing the tail reset, and waiting for the next waiter can lead to cases where we are the final waiter, and thus no next waiter arrives, leading to intermittent stalls in this path. Once the next waiter does join, we will be unblocked. In the theoretical case when the next waiter never joins, we risk stalling indefinitely.

This can only happen for ABBA deadlocks, since entry into the wait queue is guarded with AA checks. A precise sequence of executions leading up to this scenario can be:

CPU 0 holds lock A. CPU 1 holds lock B. CPU 2 attempts lock B, becomes the pending waiter for B. CPU 0 attempts lock B. B has locked+pending bits set, thus CPU 0 queues. CPU 1 attempts lock A. CPU 0 detects an ABBA deadlock.

Once deadlock detection happens for CPU 0, it will sit waiting for the next waiter in the queue to populate node->next, which will experience delays until such a waiter arrives.

Fix this by adjusting the logic for the check for deadlocks preceding the waitq_timeout label. It would make sense to consolidate code for both cases and use 'ret' to distinguish the value being propagated, but that is left as an exercise for a future refactoring task to avoid diff noise in this patch.

In the Linux kernel, the following vulnerability has been resolved:

rqspinlock: Reset tail when preserving queue on deadlock

Currently, the destruction of the waiter queue is suppressed for rqspinlock in cases where a deadlock is detected. Deadlock checks happen relatively frequently (on entry for AA, within 1ms for ABBA), and waiter threads may not be involved in locking scenarios involving deadlocks. Thus, it is useful to not flush the queue and let other waiters take a stab at acquiring the lock after we detect a deadlock and exit.

However, we need to follow the same logic as what we did previously for the waitq_timeout label: reset the tail, and if we cannot, signal the next waiter appropriately. In case of deadlocks, this signal would just mark the MCS node as unlocked, and in case of timeouts, it would signal RES_TIMEOUT_VAL. The difference thus is in the value propagated, which decides whether the queue remains active or gets flushed.

Not doing the tail reset, and waiting for the next waiter can lead to cases where we are the final waiter, and thus no next waiter arrives, leading to intermittent stalls in this path. Once the next waiter does join, we will be unblocked. In the theoretical case when the next waiter never joins, we risk stalling indefinitely.

This can only happen for ABBA deadlocks, since entry into the wait queue is guarded with AA checks. A precise sequence of executions leading up to this scenario can be:

CPU 0 holds lock A. CPU 1 holds lock B. CPU 2 attempts lock B, becomes the pending waiter for B. CPU 0 attempts lock B. B has locked+pending bits set, thus CPU 0 queues. CPU 1 attempts lock A. CPU 0 detects an ABBA deadlock.

Once deadlock detection happens for CPU 0, it will sit waiting for the next waiter in the queue to populate node->next, which will experience delays until such a waiter arrives.

Fix this by adjusting the logic for the check for deadlocks preceding the waitq_timeout label. It would make sense to consolidate code for both cases and use 'ret' to distinguish the value being propagated, but that is left as an exercise for a future refactoring task to avoid diff noise in this patch.

In the Linux kernel, the following vulnerability has been resolved: rqspinlock: Reset tail when preserving queue on deadlock Currently, the destruction of the waiter queue is suppressed for rqspinlock in cases where a deadlock is detected. Deadlock checks happen relatively frequently (on entry for AA, within 1ms for ABBA), and waiter threads may not be involved in locking scenarios involving deadlocks. Thus, it is useful to not flush the queue and let other waiters take a stab at acquiring the lock after we detect a deadlock and exit. However, we need to follow the same logic as what we did previously for the waitq_timeout label: reset the tail, and if we cannot, signal the next waiter appropriately. In case of deadlocks, this signal would just mark the MCS node as unlocked, and in case of timeouts, it would signal RES_TIMEOUT_VAL. The difference thus is in the value propagated, which decides whether the queue remains active or gets flushed. Not doing the tail reset, and waiting for the next waiter can lead to cases where we are the final waiter, and thus no next waiter arrives, leading to intermittent stalls in this path. Once the next waiter does join, we will be unblocked. In the theoretical case when the next waiter never joins, we risk stalling indefinitely. This can only happen for ABBA deadlocks, since entry into the wait queue is guarded with AA checks. A precise sequence of executions leading up to this scenario can be: CPU 0 holds lock A. CPU 1 holds lock B. CPU 2 attempts lock B, becomes the pending waiter for B. CPU 0 attempts lock B. B has locked+pending bits set, thus CPU 0 queues. CPU 1 attempts lock A. CPU 0 detects an ABBA deadlock. Once deadlock detection happens for CPU 0, it will sit waiting for the next waiter in the queue to populate node->next, which will experience delays until such a waiter arrives. Fix this by adjusting the logic for the check for deadlocks preceding the waitq_timeout label. It would make sense to consolidate code for both cases and use 'ret' to distinguish the value being propagated, but that is left as an exercise for a future refactoring task to avoid diff noise in this patch.

In the Linux kernel, the following vulnerability has been resolved: rqspinlock: Reset tail when preserving queue on deadlock Currently, the destruction of the waiter queue is suppressed for rqspinlock in cases where a deadlock is detected. Deadlock checks happen relatively frequently (on entry for AA, within 1ms for ABBA), and waiter threads may not be involved in locking scenarios involving deadlocks. Thus, it is useful to not flush the queue and let other waiters take a stab at acquiring the lock after we detect a deadlock and exit. However, we need to follow the same logic as what we did previously for the waitq_timeout label: reset the tail, and if we cannot, signal the next waiter appropriately. In case of deadlocks, this signal would just mark the MCS node as unlocked, and in case of timeouts, it would signal RES_TIMEOUT_VAL. The difference thus is in the value propagated, which decides whether the queue remains active or gets flushed. Not doing the tail reset, and waiting for the next waiter can lead to cases where we are the final waiter, and thus no next waiter arrives, leading to intermittent stalls in this path. Once the next waiter does join, we will be unblocked. In the theoretical case when the next waiter never joins, we risk stalling indefinitely. This can only happen for ABBA deadlocks, since entry into the wait queue is guarded with AA checks. A precise sequence of executions leading up to this scenario can be: CPU 0 holds lock A. CPU 1 holds lock B. CPU 2 attempts lock B, becomes the pending waiter for B. CPU 0 attempts lock B. B has locked+pending bits set, thus CPU 0 queues. CPU 1 attempts lock A. CPU 0 detects an ABBA deadlock. Once deadlock detection happens for CPU 0, it will sit waiting for the next waiter in the queue to populate node->next, which will experience delays until such a waiter arrives. Fix this by adjusting the logic for the check for deadlocks preceding the waitq_timeout label. It would make sense to consolidate code for both cases and use 'ret' to distinguish the value being propagated, but that is left as an exercise for a future refactoring task to avoid diff noise in this patch.

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems:

• USB Gadget drivers;
• Memory management;
• Multiple devices driver;
• ARM64 architecture;
• EROFS file system;
• Networking core;
• eXpress Data Path;
• ARM32 architecture;
• M68K architecture;
• MIPS architecture;
• OpenRISC architecture;
• PA-RISC architecture;
• PowerPC architecture;
• RISC-V architecture;
• S390 architecture;
• User-Mode Linux (UML);
• x86 architecture;
• Block layer subsystem;
• Cryptographic API;
• Compute Acceleration Framework;
• Intel NPU Driver;
• Speakup Console Speech Driver;
• ACPI drivers;
• Serial ATA and Parallel ATA drivers;
• Auxiliary display drivers;
• Drivers core;
• Micron PCIe SSD driver;
• Null block device driver;
• Ublk userspace block driver;
• Compressed RAM block device driver;
• Bluetooth drivers;
• Bus devices;
• AMD CDX bus driver;
• Hardware random number generator core;
• Character device driver;
• TPM device driver;
• Clock framework and drivers;
• Clocksource drivers;
• CPU frequency scaling framework;
• CPU idle management framework;
• Hardware crypto device drivers;
• CXL (Compute Express Link) drivers;
• DAX dirext access to differentiated memory framework;
• DIBS (Direct Internal Buffer Sharing) drivers;
• Buffer Sharing and Synchronization framework;
• DMA engine subsystem;
• EDAC drivers;
• FireWire subsystem;
• ARM SCMI message protocol;
• ARM SCPI message protocol;
• Google firmware drivers;
• Qualcomm firmware drivers;
• FPGA Framework;
• GPIO subsystem;
• GPU drivers;
• HID subsystem;
• HSI subsystem;
• Microsoft Hyper-V drivers;
• Hardware monitoring drivers;
• CoreSight HW tracing drivers;
• I2C subsystem;
• I3C subsystem;
• IIO subsystem;
• InfiniBand drivers;
• Input Device core drivers;
• Input Device (Miscellaneous) drivers;
• Input Device (Mouse) drivers;
• On-Chip Interconnect management framework;
• IOMMU subsystem;
• Industry Pack bus drivers;
• IRQ chip drivers;
• Mailbox framework;
• Media drivers;
• MemoryStick subsystem;
• Multifunction device drivers;
• Analog Devices digital potentiometer driver;
• Broadcom VK accelerator driver;
• Fastrpc Driver;
• Amazon Nitro Secure Module driver;
• SGI GRU driver;
• MMC subsystem;
• MTD block device drivers;
• Network drivers;
• Ethernet bonding driver;
• Mellanox network drivers;
• Microsoft Azure Network Adapter (MANA) driver;
• STMicroelectronics network drivers;
• Texas Instruments network drivers;
• MediaTek network drivers;
• Near Field Communication (NFC) drivers;
• NTB driver;
• NVDIMM (Non-Volatile Memory Device) drivers;
• NVME drivers;
• Device tree and open firmware driver;
• Operating Performance Points (OPP) driver;
• PA-RISC drivers;
• PCI subsystem;
• Performance monitor drivers;
• PHY drivers;
• Pin controllers subsystem;
• Chrome hardware platform drivers;
• Mellanox platform drivers;
• Microsoft Surface platform drivers;
• x86 platform drivers;
• MediaTek PM domains;
• Power sequencing drivers;
• Power supply drivers;
• Powercap sysfs driver;
• PTP clock framework;
• PWM drivers;
• RapidIO drivers;
• Voltage and Current Regulator drivers;
• Remote Processor subsystem;
• MPAM driver;
• RPMSG subsystem;
• Real Time Clock drivers;
• S/390 drivers;
• SCSI subsystem;
• ASPEED SoC drivers;
• Samsung SoC drivers;
• SPI subsystem;
• small TFT LCD display modules;
• Greybus lights staging drivers;
• Media staging drivers;
• Realtek RTL8723BS SDIO drivers;
• TCM subsystem;
• Trusted Execution Environment drivers;
• Thermal drivers;
• Thunderbolt and USB4 drivers;
• TTY drivers;
• UFS subsystem;
• Userspace I/O drivers;
• USB DSL drivers;
• Cypress C67X00 USB…

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems:

• USB Gadget drivers;
• Memory management;
• Multiple devices driver;
• ARM64 architecture;
• EROFS file system;
• Networking core;
• eXpress Data Path;
• ARM32 architecture;
• M68K architecture;
• MIPS architecture;
• OpenRISC architecture;
• PA-RISC architecture;
• PowerPC architecture;
• RISC-V architecture;
• S390 architecture;
• User-Mode Linux (UML);
• x86 architecture;
• Block layer subsystem;
• Cryptographic API;
• Compute Acceleration Framework;
• Intel NPU Driver;
• Speakup Console Speech Driver;
• ACPI drivers;
• Serial ATA and Parallel ATA drivers;
• Auxiliary display drivers;
• Drivers core;
• Micron PCIe SSD driver;
• Null block device driver;
• Ublk userspace block driver;
• Compressed RAM block device driver;
• Bluetooth drivers;
• Bus devices;
• AMD CDX bus driver;
• Hardware random number generator core;
• Character device driver;
• TPM device driver;
• Clock framework and drivers;
• Clocksource drivers;
• CPU frequency scaling framework;
• CPU idle management framework;
• Hardware crypto device drivers;
• CXL (Compute Express Link) drivers;
• DAX dirext access to differentiated memory framework;
• DIBS (Direct Internal Buffer Sharing) drivers;
• Buffer Sharing and Synchronization framework;
• DMA engine subsystem;
• EDAC drivers;
• FireWire subsystem;
• ARM SCMI message protocol;
• ARM SCPI message protocol;
• Google firmware drivers;
• Qualcomm firmware drivers;
• FPGA Framework;
• GPIO subsystem;
• GPU drivers;
• HID subsystem;
• HSI subsystem;
• Microsoft Hyper-V drivers;
• Hardware monitoring drivers;
• CoreSight HW tracing drivers;
• I2C subsystem;
• I3C subsystem;
• IIO subsystem;
• InfiniBand drivers;
• Input Device core drivers;
• Input Device (Miscellaneous) drivers;
• Input Device (Mouse) drivers;
• On-Chip Interconnect management framework;
• IOMMU subsystem;
• Industry Pack bus drivers;
• IRQ chip drivers;
• Mailbox framework;
• Media drivers;
• MemoryStick subsystem;
• Multifunction device drivers;
• Analog Devices digital potentiometer driver;
• Broadcom VK accelerator driver;
• Fastrpc Driver;
• Amazon Nitro Secure Module driver;
• SGI GRU driver;
• MMC subsystem;
• MTD block device drivers;
• Network drivers;
• Ethernet bonding driver;
• Mellanox network drivers;
• Microsoft Azure Network Adapter (MANA) driver;
• STMicroelectronics network drivers;
• Texas Instruments network drivers;
• MediaTek network drivers;
• Near Field Communication (NFC) drivers;
• NTB driver;
• NVDIMM (Non-Volatile Memory Device) drivers;
• NVME drivers;
• Device tree and open firmware driver;
• Operating Performance Points (OPP) driver;
• PA-RISC drivers;
• PCI subsystem;
• Performance monitor drivers;
• PHY drivers;
• Pin controllers subsystem;
• Chrome hardware platform drivers;
• Mellanox platform drivers;
• Microsoft Surface platform drivers;
• x86 platform drivers;
• MediaTek PM domains;
• Power sequencing drivers;
• Power supply drivers;
• Powercap sysfs driver;
• PTP clock framework;
• PWM drivers;
• RapidIO drivers;
• Voltage and Current Regulator drivers;
• Remote Processor subsystem;
• MPAM driver;
• RPMSG subsystem;
• Real Time Clock drivers;
• S/390 drivers;
• SCSI subsystem;
• ASPEED SoC drivers;
• Samsung SoC drivers;
• SPI subsystem;
• small TFT LCD display modules;
• Greybus lights staging drivers;
• Media staging drivers;
• Realtek RTL8723BS SDIO drivers;
• TCM subsystem;
• Trusted Execution Environment drivers;
• Thermal drivers;
• Thunderbolt and USB4 drivers;
• TTY drivers;
• UFS subsystem;
• Userspace I/O drivers;
• USB DSL drivers;
• Cypress C67X00 USB…