CVE-2024-56593

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

wifi: brcmfmac: Fix oops due to NULL pointer dereference in brcmf_sdiod_sglist_rw()

This patch fixes a NULL pointer dereference bug in brcmfmac that occurs

when a high 'sd_sgentry_align' value applies (e.g. 512) and a lot of queued SKBs

are sent from the pkt queue.

The problem is the number of entries in the pre-allocated sgtable, it is

nents = max(rxglom_size, txglom_size) + max(rxglom_size, txglom_size) >> 4 + 1.

Given the default [rt]xglom_size=32 it's actually 35 which is too small.

Worst case, the pkt queue can end up with 64 SKBs. This occurs when a new SKB

is added for each original SKB if tailroom isn't enough to hold tail_pad.

At least one sg entry is needed for each SKB. So, eventually the "skb_queue_walk loop"

in brcmf_sdiod_sglist_rw may run out of sg entries. This makes sg_next return

NULL and this causes the oops.

The patch sets nents to max(rxglom_size, txglom_size) * 2 to be able handle

the worst-ca

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. 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.

Affected Products

References