diff options
| -rw-r--r-- | arch/i386/kernel/entry.S | 4 | ||||
| -rw-r--r-- | include/asm-i386/system.h | 8 |
2 files changed, 11 insertions, 1 deletions
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S index 37a7d2e..87f9f60 100644 --- a/arch/i386/kernel/entry.S +++ b/arch/i386/kernel/entry.S @@ -209,6 +209,10 @@ ENTRY(ret_from_fork) GET_THREAD_INFO(%ebp) popl %eax CFI_ADJUST_CFA_OFFSET -4 + pushl $0x0202 # Reset kernel eflags + CFI_ADJUST_CFA_OFFSET 4 + popfl + CFI_ADJUST_CFA_OFFSET -4 jmp syscall_exit CFI_ENDPROC diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h index 49928eb..098bcee 100644 --- a/include/asm-i386/system.h +++ b/include/asm-i386/system.h @@ -11,9 +11,14 @@ 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 */ \ @@ -21,6 +26,7 @@ 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), \ |