CVE-2025-38440

/// Technical 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_c

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References