Linux Kernel CVE-2025-39998

In the Linux kernel, the following vulnerability has been resolved:

scsi: target: target_core_configfs: Add length check to avoid buffer overflow

A buffer overflow arises from the usage of snprintf to write into the buffer "buf" in target_lu_gp_members_show function located in /drivers/target/target_core_configfs.c. This buffer is allocated with size LU_GROUP_NAME_BUF (256 bytes).

snprintf(...) formats multiple strings into buf with the HBA name (hba->hba_group.cg_item), a slash character, a devicename (dev-> dev_group.cg_item) and a newline character, the total formatted string length may exceed the buffer size of 256 bytes.

Since snprintf() returns the total number of bytes that would have been written (the length of %s/%sn ), this value may exceed the buffer length (256 bytes) passed to memcpy(), this will ultimately cause function memcpy reporting a buffer overflow error.

An additional check of the return value of snprintf() can avoid this buffer overflow.

The affected product is the mainline and stable Linux kernel, specifically the target_core (LIO) module in drivers/target/target_core_configfs.c, on systems that have the SCSI target subsystem configured. No CPE strings, exact version ranges, or a formal vendor advisory URL were supplied in the input; affected versions are only inferable from the nine stable-tree fix commits at git.kernel.org (e.g. https://git.kernel.org/stable/c/f03aa5e39da7d045615b3951d2a6ca1d7132f881 and the parallel backports 27e06650a5ea, 4b292286949588, 53c6351597e6, 764a91e2fc96, a150275831b7, ddc79fba132b, e6eeee5dc0d9, e73fe0eefac3), whose count indicates the fix was backported across several supported stable branches.