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.
References
Configurations
Configuration 1 (hide)
|
History
27 Apr 2026, 20:13
| Type | Values Removed | Values Added |
|---|---|---|
| First Time |
Linux
Linux linux Kernel |
|
| References | () https://git.kernel.org/stable/c/10d12b9240ebf96c785f0e2e4228318cd5f3a3eb - Patch | |
| References | () https://git.kernel.org/stable/c/275bdf762e82082f064e60a92448fa2ac43cf95b - Patch | |
| References | () https://git.kernel.org/stable/c/2c91b39912278d0878f9ba60ba04d2518b18a08d - Patch | |
| References | () https://git.kernel.org/stable/c/513e06735f5be575b409d195822195348b164e48 - Patch | |
| References | () https://git.kernel.org/stable/c/51f4e090b9f87b40c21b6daadb5c06e6c0a07b67 - Patch | |
| References | () https://git.kernel.org/stable/c/6fca757c20396dc2e604dcc61922264e9e3dc803 - Patch | |
| References | () https://git.kernel.org/stable/c/a2b68a9a476b9544ff31f1fbcd5d80867a8a5e2f - Patch | |
| References | () https://git.kernel.org/stable/c/b7b8012193fd98236d7ae05d4b553f010a77b2ef - Patch | |
| CPE | cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:3.2:-:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* |
|
| CWE | CWE-190 |
27 Apr 2026, 15:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 9.8 |
24 Apr 2026, 15:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-04-24 15:16
Updated : 2026-04-27 20:13
NVD link : CVE-2026-31649
Mitre link : CVE-2026-31649
CVE.ORG link : CVE-2026-31649
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-190
Integer Overflow or Wraparound