CVE-2026-68435

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

LoongArch: Fix address space mismatch in kexec command line lookup

When searching the loaded segments for the "kexec" command line marker, the kexecload(2) path (filemode == 0) passes the user-space segment buffer straight to strncmp() through a bogus (char __user *) cast. This dereferences a user pointer in kernel context, which is wrong and is flagged by sparse:

arch/loongarch/kernel/machine_kexec.c:84:51: sparse: incorrect type in argument 2 (different address spaces) @@ expected char const * @@ got char [noderef] __user *

Here copy the marker-sized prefix of each segment into a small on-stack buffer with copyfromuser() before comparing, and skip segments that fault. The subsequent copyfromuser() that stages the full command line into the safe area is left unchanged.