CVE-2025-38440
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-07-25

Last updated on: 2025-11-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Fix race between DIM disable and net_dim() There's a race between disabling DIM and NAPI callbacks using the dim pointer on the RQ or SQ. If NAPI checks the DIM state bit and sees it still set, it assumes `rq->dim` or `sq->dim` is valid. But if DIM gets disabled right after that check, the pointer might already be set to NULL, leading to a NULL pointer dereference in net_dim(). Fix this by calling `synchronize_net()` before freeing the DIM context. This ensures all in-progress NAPI callbacks are finished before the pointer is cleared. Kernel log: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:net_dim+0x23/0x190 ... Call Trace: <TASK> ? __die+0x20/0x60 ? page_fault_oops+0x150/0x3e0 ? common_interrupt+0xf/0xa0 ? sysvec_call_function_single+0xb/0x90 ? exc_page_fault+0x74/0x130 ? asm_exc_page_fault+0x22/0x30 ? net_dim+0x23/0x190 ? mlx5e_poll_ico_cq+0x41/0x6f0 [mlx5_core] ? sysvec_apic_timer_interrupt+0xb/0x90 mlx5e_handle_rx_dim+0x92/0xd0 [mlx5_core] mlx5e_napi_poll+0x2cd/0xac0 [mlx5_core] ? mlx5e_poll_ico_cq+0xe5/0x6f0 [mlx5_core] busy_poll_stop+0xa2/0x200 ? mlx5e_napi_poll+0x1d9/0xac0 [mlx5_core] ? mlx5e_trigger_irq+0x130/0x130 [mlx5_core] __napi_busy_loop+0x345/0x3b0 ? sysvec_call_function_single+0xb/0x90 ? asm_sysvec_call_function_single+0x16/0x20 ? sysvec_apic_timer_interrupt+0xb/0x90 ? pcpu_free_area+0x1e4/0x2e0 napi_busy_loop+0x11/0x20 xsk_recvmsg+0x10c/0x130 sock_recvmsg+0x44/0x70 __sys_recvfrom+0xbc/0x130 ? __schedule+0x398/0x890 __x64_sys_recvfrom+0x20/0x30 do_syscall_64+0x4c/0x100 entry_SYSCALL_64_after_hwframe+0x4b/0x53 ... ---[ end trace 0000000000000000 ]--- ... ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
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Meta Information
Published
2025-07-25
Last Modified
2025-11-19
Generated
2026-05-07
AI Q&A
2025-07-25
EPSS Evaluated
2026-05-05
NVD
CVE-2025-38440
Affected Vendors & Products
Showing 7 associated CPEs
Vendor Product Version / Range
linux linux_kernel 6.16
linux linux_kernel 6.16
linux linux_kernel 6.16
linux linux_kernel 6.16
linux linux_kernel 6.16
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-362 The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
Attack-Flow Graph
AI Powered Q&A
What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, update the Linux kernel to a version that includes the fix which calls synchronize_net() before freeing the DIM context. This ensures all in-progress NAPI callbacks are finished before the pointer is cleared, preventing the NULL pointer dereference. Until an update is applied, monitor kernel logs for crashes and consider disabling affected network drivers if feasible.


Can you explain this vulnerability to me?

This vulnerability is a race condition in the Linux kernel's mlx5e network driver related to disabling Dynamic Interrupt Moderation (DIM) and NAPI callbacks. When DIM is disabled, there is a timing issue where NAPI may still see the DIM pointer as valid, but it could have already been set to NULL, causing a NULL pointer dereference in the net_dim() function. This can lead to kernel crashes. The fix involves ensuring all in-progress NAPI callbacks complete before the DIM pointer is cleared by calling synchronize_net() before freeing the DIM context.


How can this vulnerability impact me? :

This vulnerability can cause kernel NULL pointer dereferences leading to kernel crashes or panics. This can result in system instability, denial of service, or unexpected reboots on affected Linux systems using the mlx5e network driver, potentially disrupting network operations and overall system availability.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring the kernel logs for NULL pointer dereference errors related to net_dim(), specifically messages like 'BUG: kernel NULL pointer dereference' and call traces involving net_dim and mlx5_core modules. You can check kernel logs using commands such as 'dmesg | grep net_dim' or 'journalctl -k | grep net_dim' to identify these errors.


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