CVE-2025-39928

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
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*

History

10 Dec 2025, 21:50

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 5.5
References () https://git.kernel.org/stable/c/06418cb5a1a542a003fdb4ad8e76ea542d57cfba - () https://git.kernel.org/stable/c/06418cb5a1a542a003fdb4ad8e76ea542d57cfba - Patch
References () https://git.kernel.org/stable/c/c91382328fc89f73144d5582f2d8f1dd3e41c8f7 - () https://git.kernel.org/stable/c/c91382328fc89f73144d5582f2d8f1dd3e41c8f7 - Patch
CPE cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*
CWE CWE-191
First Time Linux
Linux linux Kernel

01 Oct 2025, 08:15

Type Values Removed Values Added
New CVE

Information

Published : 2025-10-01 08:15

Updated : 2025-12-10 21:50


NVD link : CVE-2025-39928

Mitre link : CVE-2025-39928

CVE.ORG link : CVE-2025-39928


JSON object : View

Products Affected

linux

  • linux_kernel
CWE
CWE-191

Integer Underflow (Wrap or Wraparound)