Description
In the Linux kernel, the following vulnerability has been resolved:
i2c: rtl9300: ensure data length is within supported range
Add an explicit check for the xfer length to 'rtl9300_i2c_config_xfer'
to ensure the data length isn't within the supported range. In
particular a data length of 0 is not supported by the hardware and
causes unintended or destructive behaviour.
This limitation becomes obvious when looking at the register
documentation [1]. 4 bits are reserved for DATA_WIDTH and the value
of these 4 bits is used as N + 1, allowing a data length range of
1 <= len <= 16.
Affected by this is the SMBus Quick Operation which works with a data
length of 0. Passing 0 as the length causes an underflow of the value
due to:
(len - 1) & 0xf
and effectively specifying a transfer length of 16 via the registers.
This causes a 16-byte write operation instead of a Quick Write. For
example, on SFP modules without write-protected EEPROM this soft-bricks
them by overwriting some initial bytes.
For completeness, also add a quirk for the zero length.
[1] https://svanheule.net/realtek/longan/register/i2c_mst1_ctrl2
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 6.13 | 6.16.8 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 6.16.8-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | linux-azure-fde | No fix yet | — |
| Ubuntu 24.04 LTS | linux-intel +18 | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv +32 | No fix yet | — |
| Ubuntu 20.04 LTS | linux-gke +28 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp +14 | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime-6.14 | No fix yet | — |
Advisories 1
- WID-SEC-2025-2170 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026