Commit 5fbd5fc4 authored Jun 29, 2017 by Dave Martin Committed by Will Deacon Jun 29, 2017

arm64: ptrace: Fix incorrect get_user() use in compat_vfp_set()



Now that compat_vfp_get() uses the regset API to copy the FPSCR
value out to userspace, compat_vfp_set() looks inconsistent.  In
particular, compat_vfp_set() will fail if called with kbuf != NULL
&& ubuf == NULL (which is valid usage according to the regset API).

This patch fixes compat_vfp_set() to use user_regset_copyin(),
similarly to compat_vfp_get().

This also squashes a sparse warning triggered by the cast that
drops __user when calling get_user().

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

parent 16d38acb

arch/arm64/kernel/ptrace.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -935,15 +935,17 @@ static int compat_vfp_set(struct task_struct *target,
		{
		struct user_fpsimd_state *uregs;
		compat_ulong_t fpscr;
		int ret;
		int ret, vregs_end_pos;

		uregs = &target->thread.fpsimd_state.user_fpsimd;

		vregs_end_pos = VFP_STATE_SIZE - sizeof(compat_ulong_t);
		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, uregs, 0,
		VFP_STATE_SIZE - sizeof(compat_ulong_t));
		vregs_end_pos);

		if (count && !ret) {
		ret = get_user(fpscr, (compat_ulong_t *)ubuf);
		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &fpscr,
		vregs_end_pos, VFP_STATE_SIZE);
		if (!ret) {
		uregs->fpsr = fpscr & VFP_FPSCR_STAT_MASK;
		uregs->fpcr = fpscr & VFP_FPSCR_CTRL_MASK;