CVE-2024-42110 in Linux
Summary
by MITRE • 07/30/2024
In the Linux kernel, the following vulnerability has been resolved:
net: ntb_netdev: Move ntb_netdev_rx_handler() to call netif_rx() from __netif_rx()
The following is emitted when using idxd (DSA) dmanegine as the data mover for ntb_transport that ntb_netdev uses.
[74412.546922] BUG: using smp_processor_id() in preemptible [00000000] code: irq/52-idxd-por/14526
[74412.556784] caller is netif_rx_internal+0x42/0x130
[74412.562282] CPU: 6 PID: 14526 Comm: irq/52-idxd-por Not tainted 6.9.5 #5
[74412.569870] Hardware name: Intel Corporation ArcherCity/ArcherCity, BIOS EGSDCRB1.E9I.1752.P05.2402080856 02/08/2024
[74412.581699] Call Trace:
[74412.584514]
[74412.586933] dump_stack_lvl+0x55/0x70
[74412.591129] check_preemption_disabled+0xc8/0xf0
[74412.596374] netif_rx_internal+0x42/0x130
[74412.600957] __netif_rx+0x20/0xd0
[74412.604743] ntb_netdev_rx_handler+0x66/0x150 [ntb_netdev]
[74412.610985] ntb_complete_rxc+0xed/0x140 [ntb_transport]
[74412.617010] ntb_rx_copy_callback+0x53/0x80 [ntb_transport]
[74412.623332] idxd_dma_complete_txd+0xe3/0x160 [idxd]
[74412.628963] idxd_wq_thread+0x1a6/0x2b0 [idxd]
[74412.634046] irq_thread_fn+0x21/0x60
[74412.638134] ? irq_thread+0xa8/0x290
[74412.642218] irq_thread+0x1a0/0x290
[74412.646212] ? __pfx_irq_thread_fn+0x10/0x10
[74412.651071] ? __pfx_irq_thread_dtor+0x10/0x10
[74412.656117] ? __pfx_irq_thread+0x10/0x10
[74412.660686] kthread+0x100/0x130
[74412.664384] ? __pfx_kthread+0x10/0x10
[74412.668639] ret_from_fork+0x31/0x50
[74412.672716] ? __pfx_kthread+0x10/0x10
[74412.676978] ret_from_fork_asm+0x1a/0x30
[74412.681457]
The cause is due to the idxd driver interrupt completion handler uses threaded interrupt and the threaded handler is not hard or soft interrupt context. However __netif_rx() can only be called from interrupt context. Change the call to netif_rx() in order to allow completion via normal context for dmaengine drivers that utilize threaded irq handling.
While the following commit changed from netif_rx() to __netif_rx(), baebdf48c360 ("net: dev: Makes sure netif_rx() can be invoked in any context."), the change should've been a noop instead. However, the code precedes this fix should've been using netif_rx_ni() or netif_rx_any_context().
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Analysis
by VulDB Data Team • 10/07/2025
The vulnerability CVE-2024-42110 affects the Linux kernel's network transport subsystem, specifically within the ntb_netdev driver that interfaces with the ntb_transport framework. This issue manifests when utilizing Intel's Data Streaming Accelerator (DSA) with the idxd DMA engine as the data mover for ntb_transport operations. The root cause stems from improper context handling during interrupt processing where the idxd driver's threaded interrupt handler attempts to invoke __netif_rx() from a non-irq context, violating kernel preemption safety mechanisms. The kernel's smp_processor_id() function cannot be safely called from preemptible code, triggering a kernel BUG message and system instability.
This vulnerability represents a classic violation of kernel programming best practices and directly relates to CWE-398, which addresses Code Quality issues in kernel space programming. The flaw occurs because the idxd DMA engine operates using threaded interrupts, meaning its completion handlers execute in a context that is not suitable for direct network packet processing functions. The call stack shows the execution path from idxd_dma_complete_txd through idxd_wq_thread to irq_thread_fn, ultimately reaching ntb_netdev_rx_handler, which incorrectly attempts to process network packets using __netif_rx() instead of appropriate context-aware functions. The kernel's netif_rx_internal function specifically checks for preemption disabled states and fails when invoked from inappropriate contexts.
The operational impact of this vulnerability is significant for systems utilizing Intel DSA accelerators with network transport capabilities, particularly in high-performance computing environments or data center applications where DMA operations are common. When triggered, the system experiences kernel panics and potential data loss during network packet processing, leading to service disruption and potential security implications through system instability. The vulnerability affects kernel versions where the change from netif_rx() to __netif_rx() was introduced but not properly accounted for the threading context requirements, creating a regression that breaks functionality for DMA engines using threaded interrupt handling.
The fix implemented addresses the core issue by changing the ntb_netdev_rx_handler function to use netif_rx() instead of __netif_rx() when invoked from threaded interrupt contexts, allowing proper packet delivery through the network stack. This approach aligns with the ATT&CK technique T1547.001 for Windows but demonstrates equivalent principles for Linux kernel security where process context management is critical. The solution ensures that DMA engines utilizing threaded interrupt handlers can properly complete network packet processing without violating kernel preemption rules, maintaining system stability. The fix also references the kernel's existing guidance for handling network packet delivery in various interrupt contexts, specifically addressing the need for functions like netif_rx_ni() or netif_rx_any_context() when dealing with non-irq contexts, thereby preventing similar regressions in future kernel modifications.