CVE-2026-97953

/// Technical description

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

net: stmmac: fix TX descriptor availability check for TSO traffic

stmmac_tso_xmit() estimates the number of free TX descriptors required by

a TSO skb as:

(skb->len - proto_hdr_len) / TSO_MAX_BUFF_SIZE + 1

which assumes the payload is split into TSO_MAX_BUFF_SIZE chunks. This

underestimates the descriptors actually consumed by stmmac_tso_allocator(),

since each fragment is mapped individually and so it needs at least one

descriptor regardless of its size. Moreover, one descriptor is used for

the L2/L3/L4 headers and, when the MSS changes, one more is consumed for

the MSS context descriptor.

For a highly fragmented TSO skb the check can therefore pass even when the

ring has too few free slots. stmmac_tso_allocator() then writes past the

available descriptors, overwriting descriptors still owned by the DMA

engine, corrupting the TX ring.

Add stmmac_tso_get_num_desc() to compute the exact number of descriptors

needed

/// 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