net: stmmac: fix integer underflow in chain mode (Linux Linux)

CVE-2026-31649
CRITICAL 9.8

En bref

Source
NVD
EPSS
EPSS 0.46 % · centile 40 ()
État
PUBLISHED
Publiée
Mise à jour
Attribuée par
Linux
Statut NVD
Modified

Description

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix integer underflow in chain mode The jumbo_frm() chain-mode implementation unconditionally computes len = nopaged_len - bmax; where nopaged_len = skb_headlen(skb) (linear bytes only) and bmax is BUF_SIZE_8KiB or BUF_SIZE_2KiB. However, the caller stmmac_xmit() decides to invoke jumbo_frm() based on skb->len (total length including page fragments): is_jumbo = stmmac_is_jumbo_frm(priv, skb->len, enh_desc); When a packet has a small linear portion (nopaged_len <= bmax) but a large total length due to page fragments (skb->len > bmax), the subtraction wraps as an unsigned integer, producing a huge len value (~0xFFFFxxxx). This causes the while (len != 0) loop to execute hundreds of thousands of iterations, passing skb->data + bmax * i pointers far beyond the skb buffer to dma_map_single(). On IOMMU-less SoCs (the typical deployment for stmmac), this maps arbitrary kernel memory to the DMA engine, constituting a kernel memory disclosure and potential memory corruption from hardware. Fix this by introducing a buf_len local variable clamped to min(nopaged_len, bmax). Computing len = nopaged_len - buf_len is then always safe: it is zero when the linear portion fits within a single descriptor, causing the while (len != 0) loop to be skipped naturally, and the fragment loop in stmmac_xmit() handles page fragments afterward.

Faiblesses (CWE)

  • CWE-190 — Débordement d'entier

Références

Scores

VersionScoreVecteurÉvalué par
CVSS 3.1CRITICAL 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HLinux
CVSS 3.1CRITICAL 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HNVD · 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Secondary)

Références européennes

Avis du CERT-FR

Configurations affectées (CPE NVD)

Produits affectés

ProduitVersions
Linux · Linuxaffected 286a837217204b1ef105e3a554d0757e4fdfaac1 < 513e06735f5be575b409d195822195348b164e48 ; affected 286a837217204b1ef105e3a554d0757e4fdfaac1 < 275bdf762e82082f064e60a92448fa2ac43cf95b ; affected 286a837217204b1ef105e3a554d0757e4fdfaac1 < a2b68a9a476b9544ff31f1fbcd5d80867a8a5e2f ; affected 286a837217204b1ef105e3a554d0757e4fdfaac1 < b7b8012193fd98236d7ae05d4b553f010a77b2ef ; affected 286a837217204b1ef105e3a554d0757e4fdfaac1 < 2c91b39912278d0878f9ba60ba04d2518b18a08d ; affected 286a837217204b1ef105e3a554d0757e4fdfaac1 < 6fca757c20396dc2e604dcc61922264e9e3dc803
Linux · Linuxaffected 3.2 ; unaffected 0 < 3.2 ; unaffected 5.10.253 ≤ 5.10.* ; unaffected 5.15.203 ≤ 5.15.* ; unaffected 6.1.169 ≤ 6.1.* ; unaffected 6.6.135 ≤ 6.6.*

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD