linux-kernel - [RFC PATCH v1 19/19] powerpc/signal32: Switch swap_context() to user_access

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Date:   Wed, 12 Aug 2020 12:06:11 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, ldv@...linux.org,
        viro@...iv.linux.org.uk
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [RFC PATCH v1 19/19] powerpc/signal32: Switch swap_context() to
 user_access_begin() logic

As this was the last user of put_sigset_t(), remove it as well.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/signal_32.c | 24 ++++++++++--------------
 1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 6cbff0293ff4..399d823782cf 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -82,11 +82,6 @@
  * Functions for flipping sigsets (thanks to brain dead generic
  * implementation that makes things simple for little endian only)
  */
-static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
-{
-	return put_compat_sigset(uset, set, sizeof(*uset));
-}
-
 #define unsafe_put_sigset_t	unsafe_put_compat_sigset
 
 static inline int get_sigset_t(sigset_t *set,
@@ -140,11 +135,6 @@ static inline int restore_general_regs(struct pt_regs *regs,
 
 #define GP_REGS_SIZE	min(sizeof(elf_gregset_t), sizeof(struct pt_regs))
 
-static inline int put_sigset_t(sigset_t __user *uset, sigset_t *set)
-{
-	return copy_to_user(uset, set, sizeof(*uset));
-}
-
 #define unsafe_put_sigset_t(uset, set, label) do { 			\
 	sigset_t __user *__us = uset	;				\
 	const sigset_t *__s = set;					\
@@ -1012,11 +1002,13 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
 		 */
 		mctx = (struct mcontext __user *)
 			((unsigned long) &old_ctx->uc_mcontext & ~0xfUL);
-		if (!access_ok(old_ctx, ctx_size)
-		    || save_user_regs(regs, mctx, NULL, 0, ctx_has_vsx_region)
-		    || put_sigset_t(&old_ctx->uc_sigmask, &current->blocked)
-		    || __put_user(to_user_ptr(mctx), &old_ctx->uc_regs))
+		if (save_user_regs(regs, mctx, NULL, 0, ctx_has_vsx_region))
+			return -EFAULT;
+		if (!user_write_access_begin(old_ctx, ctx_size))
 			return -EFAULT;
+		unsafe_put_sigset_t(&old_ctx->uc_sigmask, &current->blocked, failed);
+		unsafe_put_user(to_user_ptr(mctx), &old_ctx->uc_regs, failed);
+		user_write_access_end();
 	}
 	if (new_ctx == NULL)
 		return 0;
@@ -1040,6 +1032,10 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
 
 	set_thread_flag(TIF_RESTOREALL);
 	return 0;
+
+failed:
+	user_write_access_end();
+	return -EFAULT;
 }
 
 #ifdef CONFIG_PPC64
-- 
2.25.0