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Acknowledged

LIN1021-12797 : Security Advisory - linux - CVE-2024-56593

Created: Dec 27, 2024    Updated: Jan 20, 2025
Found In Version: 10.21.20.1
Severity: Standard
Applicable for: Wind River Linux LTS 21
Component/s: Kernel

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-case.
Btw. this requires only 64-35=29 * 16 (or 20 if CONFIG_NEED_SG_DMA_LENGTH) = 464
additional bytes of memory.

CREATE(Triage):(User=admin) [CVE-2024-56593 (https://nvd.nist.gov/vuln/detail/CVE-2024-56593)

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