In the Linux kernel, the following vulnerability has been resolved:
riscv: Fix register corruption from uninitialized cregs on error
compat_riscv_gpr_set() calls cregs_to_regs() unconditionally, even when
user_regset_copyin() fails. Since cregs is an uninitialized stack
variable, a copyin failure causes uninitialized stack data to be written
into the target task’s pt_regs, corrupting its register state and
potentially leaking kernel stack contents.
compat_restore_sigcontext() has the same issue: it calls cregs_to_regs()
even when __copy_from_user() fails, leading to the same corruption of
the signal-returning task’s register state on error.
Only call cregs_to_regs() when the user copy succeeds.
