[PATCH v2 5/6] MIPS: Also verify sizeof `elf_fpreg_t' with PTRACE_SETREGSET

[Maciej W. Rozycki]

Complement commit d614fd58a283 ("mips/ptrace: Preserve previous 
registers for short regset write") and like with the PTRACE_GETREGSET 
ptrace(2) request also apply a BUILD_BUG_ON check for the size of the 
`elf_fpreg_t' type in the PTRACE_SETREGSET request handler.

Cc: stable@xxxxxxxxxxxxxxx # v4.11+
Fixes: d614fd58a283 ("mips/ptrace: Preserve previous registers for short regset write")
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxx>
---

No changes from v1.

---
 arch/mips/kernel/ptrace.c |    1 +
 1 file changed, 1 insertion(+)

linux-mips-nt-prfpreg-build-bug.diff
Index: linux-sfr-test/arch/mips/kernel/ptrace.c
===================================================================
--- linux-sfr-test.orig/arch/mips/kernel/ptrace.c	2017-11-28 23:33:33.395023000 +0000
+++ linux-sfr-test/arch/mips/kernel/ptrace.c	2017-11-28 23:52:34.944549000 +0000
@@ -438,6 +438,7 @@ static int fpr_get_msa(struct task_struc
 	u64 fpr_val;
 	int err;
 
+	BUILD_BUG_ON(sizeof(fpr_val) != sizeof(elf_fpreg_t));
 	for (i = 0; i < NUM_FPU_REGS; i++) {
 		fpr_val = get_fpr64(&target->thread.fpu.fpr[i], 0);
 		err = user_regset_copyout(pos, count, kbuf, ubuf,