[RFC][PATCH v2 18/22] x86: __setup_frame(): consolidate uaccess areas

From: Al Viro
Date: Thu Mar 26 2020 - 22:32:20 EST


From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/signal.c | 23 ++++++-----------------
1 file changed, 6 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index f4fb00bd2378..38ff834ba0d6 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -302,25 +302,16 @@ __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
{
struct sigframe __user *frame;
void __user *restorer;
- int err = 0;
void __user *fp = NULL;

frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fp);

- if (!access_ok(frame, sizeof(*frame)))
- return -EFAULT;
-
- if (__put_user(sig, &frame->sig))
+ if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;

- if (!user_access_begin(&frame->sc, sizeof(struct sigcontext)))
- return -EFAULT;
+ unsafe_put_user(sig, &frame->sig, Efault);
unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault);
- user_access_end();
-
- if (__put_user(set->sig[1], &frame->extramask[0]))
- return -EFAULT;
-
+ unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
if (current->mm->context.vdso)
restorer = current->mm->context.vdso +
vdso_image_32.sym___kernel_sigreturn;
@@ -330,7 +321,7 @@ __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
restorer = ksig->ka.sa.sa_restorer;

/* Set up to return from userspace. */
- err |= __put_user(restorer, &frame->pretcode);
+ unsafe_put_user(restorer, &frame->pretcode, Efault);

/*
* This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
@@ -339,10 +330,8 @@ __setup_frame(int sig, struct ksignal *ksig, sigset_t *set,
* reasons and because gdb uses it as a signature to notice
* signal handler stack frames.
*/
- err |= __put_user(*((u64 *)&retcode), (u64 *)frame->retcode);
-
- if (err)
- return -EFAULT;
+ unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
+ user_access_end();

/* Set up registers for signal handler */
regs->sp = (unsigned long)frame;
--
2.11.0