linux-kernel - [patch 09/12] syslets: x86, mark async unsafe syscalls

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Date:	Wed, 28 Feb 2007 22:42:07 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	linux-kernel@...r.kernel.org
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Christoph Hellwig <hch@...radead.org>,
	Andrew Morton <akpm@....com.au>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Ulrich Drepper <drepper@...hat.com>,
	Zach Brown <zach.brown@...cle.com>,
	Evgeniy Polyakov <johnpol@....mipt.ru>,
	"David S. Miller" <davem@...emloft.net>,
	Suparna Bhattacharya <suparna@...ibm.com>,
	Davide Libenzi <davidel@...ilserver.org>,
	Jens Axboe <jens.axboe@...cle.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [patch 09/12] syslets: x86, mark async unsafe syscalls

From: Ingo Molnar <mingo@...e.hu>

mark clone() and fork() as not available for async execution.
Both need an intact user context beneath them to work.

Signed-off-by: Ingo Molnar <mingo@...e.hu>
Signed-off-by: Arjan van de Ven <arjan@...ux.intel.com>
---
 arch/i386/kernel/ioport.c  |    6 ++++++
 arch/i386/kernel/ldt.c     |    3 +++
 arch/i386/kernel/process.c |    6 ++++++
 arch/i386/kernel/vm86.c    |    6 ++++++
 4 files changed, 21 insertions(+)

Index: linux/arch/i386/kernel/ioport.c
===================================================================
--- linux.orig/arch/i386/kernel/ioport.c
+++ linux/arch/i386/kernel/ioport.c
@@ -62,6 +62,9 @@ asmlinkage long sys_ioperm(unsigned long
 	struct tss_struct * tss;
 	unsigned long *bitmap;
 
+	if (async_syscall(current))
+		return -ENOSYS;
+
 	if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
 		return -EINVAL;
 	if (turn_on && !capable(CAP_SYS_RAWIO))
@@ -139,6 +142,9 @@ asmlinkage long sys_iopl(unsigned long u
 	unsigned int old = (regs->eflags >> 12) & 3;
 	struct thread_struct *t = &current->thread;
 
+	if (async_syscall(current))
+		return -ENOSYS;
+
 	if (level > 3)
 		return -EINVAL;
 	/* Trying to gain more privileges? */
Index: linux/arch/i386/kernel/ldt.c
===================================================================
--- linux.orig/arch/i386/kernel/ldt.c
+++ linux/arch/i386/kernel/ldt.c
@@ -233,6 +233,9 @@ asmlinkage int sys_modify_ldt(int func, 
 {
 	int ret = -ENOSYS;
 
+	if (async_syscall(current))
+		return -ENOSYS;
+
 	switch (func) {
 	case 0:
 		ret = read_ldt(ptr, bytecount);
Index: linux/arch/i386/kernel/process.c
===================================================================
--- linux.orig/arch/i386/kernel/process.c
+++ linux/arch/i386/kernel/process.c
@@ -750,6 +750,9 @@ struct task_struct fastcall * __switch_t
 
 asmlinkage int sys_fork(struct pt_regs regs)
 {
+	if (async_syscall(current))
+		return -ENOSYS;
+
 	return do_fork(SIGCHLD, regs.esp, &regs, 0, NULL, NULL);
 }
 
@@ -759,6 +762,9 @@ asmlinkage int sys_clone(struct pt_regs 
 	unsigned long newsp;
 	int __user *parent_tidptr, *child_tidptr;
 
+	if (async_syscall(current))
+		return -ENOSYS;
+
 	clone_flags = regs.ebx;
 	newsp = regs.ecx;
 	parent_tidptr = (int __user *)regs.edx;
Index: linux/arch/i386/kernel/vm86.c
===================================================================
--- linux.orig/arch/i386/kernel/vm86.c
+++ linux/arch/i386/kernel/vm86.c
@@ -209,6 +209,9 @@ asmlinkage int sys_vm86old(struct pt_reg
 	struct task_struct *tsk;
 	int tmp, ret = -EPERM;
 
+	if (async_syscall(current))
+		return -ENOSYS;
+
 	tsk = current;
 	if (tsk->thread.saved_esp0)
 		goto out;
@@ -239,6 +242,9 @@ asmlinkage int sys_vm86(struct pt_regs r
 	int tmp, ret;
 	struct vm86plus_struct __user *v86;
 
+	if (async_syscall(current))
+		return -ENOSYS;
+
 	tsk = current;
 	switch (regs.ebx) {
 		case VM86_REQUEST_IRQ:
-
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