Description
In the Linux kernel, the following vulnerability has been resolved: rcu: Protect ->defer_qs_iw_pending from data race On kernels built with CONFIG_IRQ_WORK=y, when rcu_read_unlock() is invoked within an interrupts-disabled region of code [1], it will invoke rcu_read_unlock_special(), which uses an irq-work handler to force the system to notice when the RCU read-side critical section actually ends. That end won't happen until interrupts are enabled at the soonest. In some kernels, such as those booted with rcutree.use_softirq=y, the irq-work handler is used unconditionally. The per-CPU rcu_data structure's ->defer_qs_iw_pending field is updated by the irq-work handler and is both read and updated by rcu_read_unlock_special(). This resulted in the following KCSAN splat: ------------------------------------------------------------------------ BUG: KCSAN: data-race in rcu_preempt_deferred_qs_handler / rcu_read_unlock_special read to 0xffff96b95f42d8d8 of 1 bytes by task 90 on cpu 8: rcu_read_unlock_special+0x175/0x260 __rcu_read_unlock+0x92/0xa0 rt_spin_unlock+0x9b/0xc0 __local_bh_enable+0x10d/0x170 __local_bh_enable_ip+0xfb/0x150 rcu_do_batch+0x595/0xc40 rcu_cpu_kthread+0x4e9/0x830 smpboot_thread_fn+0x24d/0x3b0 kthread+0x3bd/0x410 ret_from_fork+0x35/0x40 ret_from_fork_asm+0x1a/0x30 write to 0xffff96b95f42d8d8 of 1 bytes by task 88 on cpu 8: rcu_preempt_deferred_qs_handler+0x1e/0x30 irq_work_single+0xaf/0x160 run_irq_workd+0x91/0xc0 smpboot_thread_fn+0x24d/0x3b0 kthread+0x3bd/0x410 ret_from_fork+0x35/0x40 ret_from_fork_asm+0x1a/0x30 no locks held by irq_work/8/88. irq event stamp: 200272 hardirqs last enabled at (200272): [] finish_task_switch+0x131/0x320 hardirqs last disabled at (200271): [] __schedule+0x129/0xd70 softirqs last enabled at (0): [] copy_process+0x4df/0x1cc0 softirqs last disabled at (0): [] 0x0 ------------------------------------------------------------------------ The problem is that irq-work handlers run with interrupts enabled, which means that rcu_preempt_deferred_qs_handler() could be interrupted, and that interrupt handler might contain an RCU read-side critical section, which might invoke rcu_read_unlock_special(). In the strict KCSAN mode of operation used by RCU, this constitutes a data race on the ->defer_qs_iw_pending field. This commit therefore disables interrupts across the portion of the rcu_preempt_deferred_qs_handler() that updates the ->defer_qs_iw_pending field. This suffices because this handler is not a fast path.
Details
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Affected Packages
| Software | From version | Fixed in |
|---|---|---|
| linux | — | 6.8.0-100.100 |
| linux-allwinner-5.19 | — | — |
| linux-aws | — | 6.8.0-1046.49 |
| linux-aws-5.0 | — | — |
| linux-aws-5.11 | — | — |
| linux-aws-5.13 | — | — |
| linux-aws-5.15 | — | 5.15.0-1097.104~20.04.1 |
| linux-aws-5.19 | — | — |
| linux-aws-5.3 | — | — |
| linux-aws-5.4 | — | — |
| linux-aws-5.8 | — | — |
| linux-aws-6.14 | — | — |
| linux-aws-6.2 | — | — |
| linux-aws-6.5 | — | — |
| linux-aws-6.8 | — | 6.8.0-1046.49~22.04.1 |
| linux-aws-fips | — | 6.8.0-1046.49+fips1 |
| linux-aws-hwe | — | — |
| linux-azure | — | 6.8.0-1046.52 |
| linux-azure-4.15 | — | — |
| linux-azure-5.11 | — | — |
| linux-azure-5.13 | — | — |
| linux-azure-5.15 | — | 5.15.0-1102.111~20.04.1 |
| linux-azure-5.19 | — | — |
| linux-azure-5.3 | — | — |
| linux-azure-5.4 | — | — |
| linux-azure-5.8 | — | — |
| linux-azure-6.11 | — | — |
| linux-azure-6.14 | — | — |
| linux-azure-6.2 | — | — |
| linux-azure-6.5 | — | — |
| linux-azure-6.8 | — | 6.8.0-1051.57~22.04.1 |
| linux-azure-edge | — | — |
| linux-azure-fde | — | — |
| linux-azure-fde-5.15 | — | — |
| linux-azure-fde-5.19 | — | — |
| linux-azure-fde-6.14 | — | — |
| linux-azure-fde-6.17 | — | — |
| linux-azure-fde-6.2 | — | — |
| linux-azure-fde-6.8 | — | — |
| linux-azure-fips | — | 6.8.0-1046.52+fips1 |
| linux-azure-nvidia | — | — |
| linux-azure-nvidia-6.14 | — | — |
| linux-bluefield | — | — |
| linux-fips | — | 6.8.0-100.100+fips1 |
| linux-gcp | — | 6.8.0-1047.50 |
| linux-gcp-4.15 | — | — |
| linux-gcp-5.11 | — | — |
| linux-gcp-5.13 | — | — |
| linux-gcp-5.15 | — | 5.15.0-1097.106~20.04.1 |
| linux-gcp-5.19 | — | — |
| linux-gcp-5.3 | — | — |
| linux-gcp-5.4 | — | — |
| linux-gcp-5.8 | — | — |
| linux-gcp-6.11 | — | — |
| linux-gcp-6.14 | — | — |
| linux-gcp-6.2 | — | — |
| linux-gcp-6.5 | — | — |
| linux-gcp-6.8 | — | 6.8.0-1047.50~22.04.2 |
| linux-gcp-fips | — | 6.8.0-1047.50+fips1 |
| linux-gke | — | 6.8.0-1043.48 |
| linux-gke-4.15 | — | — |
| linux-gke-5.15 | — | — |
| linux-gke-5.4 | — | — |
| linux-gkeop | — | 6.8.0-1030.33 |
| linux-gkeop-5.15 | — | — |
| linux-gkeop-5.4 | — | — |
| linux-hwe | — | — |
| linux-hwe-5.11 | — | — |
| linux-hwe-5.13 | — | — |
| linux-hwe-5.15 | — | 5.15.0-163.173~20.04.1 |
| linux-hwe-5.19 | — | — |
| linux-hwe-5.4 | — | — |
| linux-hwe-5.8 | — | — |
| linux-hwe-6.11 | — | — |
| linux-hwe-6.14 | — | — |
| linux-hwe-6.2 | — | — |
| linux-hwe-6.5 | — | — |
| linux-hwe-6.8 | — | 6.8.0-100.100~22.04.1 |
| linux-hwe-edge | — | — |
| linux-ibm | — | 6.8.0-1044.44 |
| linux-ibm-5.15 | — | 5.15.0-1091.94~20.04.1 |
| linux-ibm-5.4 | — | — |
| linux-ibm-6.8 | — | 6.8.0-1044.44~22.04.1 |
| linux-intel | — | — |
| linux-intel-5.13 | — | — |
| linux-intel-iot-realtime | — | 5.15.0-1089.91 |
| linux-intel-iotg | — | 5.15.0-1092.98 |
| linux-intel-iotg-5.15 | — | 5.15.0-1092.98~20.04.1 |
| linux-iot | — | — |
| linux-kvm | — | 5.15.0-1089.94 |
| linux-lowlatency | — | 6.8.0-100.100.1 |
| linux-lowlatency-hwe-5.15 | — | 5.15.0-163.173~20.04.1 |
| linux-lowlatency-hwe-5.19 | — | — |
| linux-lowlatency-hwe-6.11 | — | — |
| linux-lowlatency-hwe-6.2 | — | — |
| linux-lowlatency-hwe-6.5 | — | — |
| linux-lowlatency-hwe-6.8 | — | 6.8.0-100.100.1~22.04.1 |
| linux-lts-xenial | — | — |
| linux-nvidia | — | 6.8.0-1046.49 |
| linux-nvidia-6.11 | — | — |
| linux-nvidia-6.2 | — | — |
| linux-nvidia-6.5 | — | — |
| linux-nvidia-6.8 | — | 6.8.0-1046.49~22.04.1 |
| linux-nvidia-lowlatency | — | 6.8.0-1046.49.1 |
| linux-nvidia-tegra | — | 6.8.0-1020.20 |
| linux-nvidia-tegra-5.15 | — | 5.15.0-1049.49~20.04.1 |
| linux-nvidia-tegra-igx | — | 5.15.0-1038.38 |
| linux-oem | — | — |
| linux-oem-5.10 | — | — |
| linux-oem-5.13 | — | — |
| linux-oem-5.14 | — | — |
| linux-oem-5.17 | — | — |
| linux-oem-5.6 | — | — |
| linux-oem-6.0 | — | — |
| linux-oem-6.1 | — | — |
| linux-oem-6.11 | — | — |
| linux-oem-6.14 | — | — |
| linux-oem-6.5 | — | — |
| linux-oem-6.8 | — | — |
| linux-oracle | — | 6.8.0-1043.44 |
| linux-oracle-5.0 | — | — |
| linux-oracle-5.11 | — | — |
| linux-oracle-5.13 | — | — |
| linux-oracle-5.15 | — | 5.15.0-1094.100~20.04.1 |
| linux-oracle-5.3 | — | — |
| linux-oracle-5.4 | — | — |
| linux-oracle-5.8 | — | — |
| linux-oracle-6.14 | — | — |
| linux-oracle-6.5 | — | — |
| linux-oracle-6.8 | — | 6.8.0-1043.44~22.04.1 |
| linux-raspi | — | 6.8.0-1047.51 |
| linux-raspi-5.4 | — | — |
| linux-raspi-realtime | — | 6.8.0-2037.38 |
| linux-raspi2 | — | — |
| linux-realtime | — | 6.8.1-1041.42 |
| linux-realtime-6.14 | — | — |
| linux-realtime-6.8 | — | 6.8.1-1041.42~22.04.1 |
| linux-riscv | — | — |
| linux-riscv-5.11 | — | — |
| linux-riscv-5.15 | — | 5.15.0-1092.96~20.04.1 |
| linux-riscv-5.19 | — | — |
| linux-riscv-5.8 | — | — |
| linux-riscv-6.14 | — | — |
| linux-riscv-6.5 | — | — |
| linux-riscv-6.8 | — | 6.8.0-100.100~22.04.1 |
| linux-starfive-5.19 | — | — |
| linux-starfive-6.2 | — | — |
| linux-starfive-6.5 | — | — |
| linux-xilinx | — | 6.8.0-1023.24 |
| linux-xilinx-zynqmp | — | 5.15.0-1061.65 |
References
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