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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
| Attack Vector | NETWORK |
|---|---|
| Attack Complexity | LOW |
| Privileges Required | NONE |
| User Interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality Impact | HIGH |
| Integrity Impact | HIGH |
| Availability Impact | HIGH |
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Type: Secondary
Exploitability Score: 3.9
Impact Score: 5.9
| Source | Type | Description |
|---|---|---|
| [email protected] | Primary |
en
CWE-190
|
| Vendor | Product | Version | Update | Type |
|---|---|---|---|---|
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdc9f6b80> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdc9f4600> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdd6ae380> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdd6a4e40> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdc9f4340> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdc9f6ec0> | Operating System |
| linux | linux_kernel | * | <built-in method update of dict object at 0x702bdd6ac400> | Operating System |
| linux | linux_kernel | 3.2 | <built-in method update of dict object at 0x702bdc3f5580> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdd6af400> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc9f6300> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc9f4c40> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc9f4ec0> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdd6a5780> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc9f4180> | Operating System |
| linux | linux_kernel | 7.0 | <built-in method update of dict object at 0x702bdc9f6640> | Operating System |
| Vulnerable | CPE |
|---|---|
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:3.2:-:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* |
| Yes | cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:* |