linux-kernel - [PATCH 3/5] MIPS: Also verify sizeof `elf_fpreg_t' with PTRACE

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Date:   Wed, 29 Nov 2017 15:20:27 +0000
From:   "Maciej W. Rozycki" <macro@...s.com>
To:     Ralf Baechle <ralf@...ux-mips.org>,
        James Hogan <james.hogan@...s.com>
CC:     Paul Burton <Paul.Burton@...s.com>,
        Alex Smith <alex@...x-smith.me.uk>,
        Dave Martin <Dave.Martin@....com>, <linux-mips@...ux-mips.org>,
        <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>
Subject: [PATCH 3/5] MIPS: Also verify sizeof `elf_fpreg_t' with
 PTRACE_SETREGSET

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@...r.kernel.org # v4.11+
Fixes: d614fd58a283 ("mips/ptrace: Preserve previous registers for short regset write")
Signed-off-by: Maciej W. Rozycki <macro@...s.com>
---
 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,