CVE-2024-35971

Published May 20, 2024

Last updated 9 months ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: net: ks8851: Handle softirqs at the end of IRQ thread to fix hang The ks8851_irq() thread may call ks8851_rx_pkts() in case there are any packets in the MAC FIFO, which calls netif_rx(). This netif_rx() implementation is guarded by local_bh_disable() and local_bh_enable(). The local_bh_enable() may call do_softirq() to run softirqs in case any are pending. One of the softirqs is net_rx_action, which ultimately reaches the driver .start_xmit callback. If that happens, the system hangs. The entire call chain is below: ks8851_start_xmit_par from netdev_start_xmit netdev_start_xmit from dev_hard_start_xmit dev_hard_start_xmit from sch_direct_xmit sch_direct_xmit from __dev_queue_xmit __dev_queue_xmit from __neigh_update __neigh_update from neigh_update neigh_update from arp_process.constprop.0 arp_process.constprop.0 from __netif_receive_skb_one_core __netif_receive_skb_one_core from process_backlog process_backlog from __napi_poll.constprop.0 __napi_poll.constprop.0 from net_rx_action net_rx_action from __do_softirq __do_softirq from call_with_stack call_with_stack from do_softirq do_softirq from __local_bh_enable_ip __local_bh_enable_ip from netif_rx netif_rx from ks8851_irq ks8851_irq from irq_thread_fn irq_thread_fn from irq_thread irq_thread from kthread kthread from ret_from_fork The hang happens because ks8851_irq() first locks a spinlock in ks8851_par.c ks8851_lock_par() spin_lock_irqsave(&ksp->lock, ...) and with that spinlock locked, calls netif_rx(). Once the execution reaches ks8851_start_xmit_par(), it calls ks8851_lock_par() again which attempts to claim the already locked spinlock again, and the hang happens. Move the do_softirq() call outside of the spinlock protected section of ks8851_irq() by disabling BHs around the entire spinlock protected section of ks8851_irq() handler. Place local_bh_enable() outside of the spinlock protected section, so that it can trigger do_softirq() without the ks8851_par.c ks8851_lock_par() spinlock being held, and safely call ks8851_start_xmit_par() without attempting to lock the already locked spinlock. Since ks8851_irq() is protected by local_bh_disable()/local_bh_enable() now, replace netif_rx() with __netif_rx() which is not duplicating the local_bh_disable()/local_bh_enable() calls.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
CWE-667

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: coresight: tmc-etr: Fix race condition between sysfs and perf mode When trying to run perf and sysfs mode simultaneously, the WARN_ON() in tmc_etr_enable_hw() is triggered sometimes: WARNING: CPU: 42 PID: 3911571 at drivers/hwtracing/coresight/coresight-tmc-etr.c:1060 tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] [..snip..] Call trace: tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] (P) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] (L) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] coresight_enable_path+0x1c8/0x218 [coresight] coresight_enable_sysfs+0xa4/0x228 [coresight] enable_source_store+0x58/0xa8 [coresight] dev_attr_store+0x20/0x40 sysfs_kf_write+0x4c/0x68 kernfs_fop_write_iter+0x120/0x1b8 vfs_write+0x2c8/0x388 ksys_write+0x74/0x108 __arm64_sys_write+0x24/0x38 el0_svc_common.constprop.0+0x64/0x148 do_el0_svc+0x24/0x38 el0_svc+0x3c/0x130 el0t_64_sync_handler+0xc8/0xd0 el0t_64_sync+0x1ac/0x1b0 ---[ end trace 0000000000000000 ]--- Since the enablement of sysfs mode is separeted into two critical regions, one for sysfs buffer allocation and another for hardware enablement, it's possible to race with the perf mode. Fix this by double check whether the perf mode's been used before enabling the hardware in sysfs mode. mode: [sysfs mode] [perf mode] tmc_etr_get_sysfs_buffer() spin_lock(&drvdata->spinlock) [sysfs buffer allocation] spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() drvdata->etr_buf = etr_perf->etr_buf spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() WARN_ON(drvdata->etr_buf) // WARN sicne etr_buf initialized at the perf side spin_unlock(&drvdata->spinlock) With this fix, we retain the check for CS_MODE_PERF in get_etr_sysfs_buf. This ensures we verify whether the perf mode's already running before we actually allocate the buffer. Then we can save the time of allocating/freeing the sysfs buffer if race with the perf mode.CVE-2026-46272