diff options
| -rw-r--r-- | arch/i386/kernel/entry.S | 2 | ||||
| -rw-r--r-- | include/asm-i386/system.h | 8 |
2 files changed, 9 insertions, 1 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index 4d704724b2f..a14218c9ec6 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -128,6 +128,8 @@ ENTRY(ret_from_fork) call schedule_tail GET_THREAD_INFO(%ebp) popl %eax + pushl $0x0202 # Reset kernel eflags + popfl jmp syscall_exit /* diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h index 399145a247f..ec36513239b 100644 --- a/include/asm-i386/system.h +++ b/include/asm-i386/system.h @@ -12,9 +12,14 @@ struct task_struct; /* one of the stranger aspects of C forward declarations.. */ extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struct task_struct *next)); +/* + * Saving eflags is important. It switches not only IOPL between tasks, + * it also protects other tasks from NT leaking through sysenter etc. + */ #define switch_to(prev,next,last) do { \ unsigned long esi,edi; \ - asm volatile("pushl %%ebp\n\t" \ + asm volatile("pushfl\n\t" /* Save flags */ \ + "pushl %%ebp\n\t" \ "movl %%esp,%0\n\t" /* save ESP */ \ "movl %5,%%esp\n\t" /* restore ESP */ \ "movl $1f,%1\n\t" /* save EIP */ \ @@ -22,6 +27,7 @@ extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struc "jmp __switch_to\n" \ "1:\t" \ "popl %%ebp\n\t" \ + "popfl" \ :"=m" (prev->thread.esp),"=m" (prev->thread.eip), \ "=a" (last),"=S" (esi),"=D" (edi) \ :"m" (next->thread.esp),"m" (next->thread.eip), \ |