linux-kernel - [RFC][PATCH v2 11/22] x86: switch ia32_setup_sigcontext() to unsafe_put

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Date:   Fri, 27 Mar 2020 02:31:54 +0000
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [RFC][PATCH v2 11/22] x86: switch ia32_setup_sigcontext() to unsafe_put_user()

From: Al Viro <viro@...iv.linux.org.uk>

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 arch/x86/ia32/ia32_signal.c | 64 +++++++++++++++++++++++----------------------
 1 file changed, 33 insertions(+), 31 deletions(-)

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 23e2c55d8a59..af673ec23a2d 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -158,38 +158,40 @@ static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
 				 void __user *fpstate,
 				 struct pt_regs *regs, unsigned int mask)
 {
-	int err = 0;
-
-	put_user_try {
-		put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
-		put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
-		put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
-		put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);
-
-		put_user_ex(regs->di, &sc->di);
-		put_user_ex(regs->si, &sc->si);
-		put_user_ex(regs->bp, &sc->bp);
-		put_user_ex(regs->sp, &sc->sp);
-		put_user_ex(regs->bx, &sc->bx);
-		put_user_ex(regs->dx, &sc->dx);
-		put_user_ex(regs->cx, &sc->cx);
-		put_user_ex(regs->ax, &sc->ax);
-		put_user_ex(current->thread.trap_nr, &sc->trapno);
-		put_user_ex(current->thread.error_code, &sc->err);
-		put_user_ex(regs->ip, &sc->ip);
-		put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
-		put_user_ex(regs->flags, &sc->flags);
-		put_user_ex(regs->sp, &sc->sp_at_signal);
-		put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
-
-		put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
-
-		/* non-iBCS2 extensions.. */
-		put_user_ex(mask, &sc->oldmask);
-		put_user_ex(current->thread.cr2, &sc->cr2);
-	} put_user_catch(err);
+	if (!user_access_begin(sc, sizeof(struct sigcontext_32)))
+		return -EFAULT;
 
-	return err;
+	unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
+	unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);
+	unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);
+	unsafe_put_user(get_user_seg(es), (unsigned int __user *)&sc->es, Efault);
+
+	unsafe_put_user(regs->di, &sc->di, Efault);
+	unsafe_put_user(regs->si, &sc->si, Efault);
+	unsafe_put_user(regs->bp, &sc->bp, Efault);
+	unsafe_put_user(regs->sp, &sc->sp, Efault);
+	unsafe_put_user(regs->bx, &sc->bx, Efault);
+	unsafe_put_user(regs->dx, &sc->dx, Efault);
+	unsafe_put_user(regs->cx, &sc->cx, Efault);
+	unsafe_put_user(regs->ax, &sc->ax, Efault);
+	unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
+	unsafe_put_user(current->thread.error_code, &sc->err, Efault);
+	unsafe_put_user(regs->ip, &sc->ip, Efault);
+	unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
+	unsafe_put_user(regs->flags, &sc->flags, Efault);
+	unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
+	unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
+
+	unsafe_put_user(ptr_to_compat(fpstate), &sc->fpstate, Efault);
+
+	/* non-iBCS2 extensions.. */
+	unsafe_put_user(mask, &sc->oldmask, Efault);
+	unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
+	user_access_end();
+	return 0;
+Efault:
+	user_access_end();
+	return -EFAULT;
 }
 
 /*
-- 
2.11.0