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| author | Andi Kleen <ak@suse.de> | 2006-09-26 10:52:41 +0200 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-09-26 10:52:41 +0200 |
| commit | 658fdbef66e5e9be79b457edc2cbbb3add840aa9 (patch) | |
| tree | 931fa9bac154671ab96762fee73b3641b1191bb8 | |
| parent | adf1423698f00d00b267f7dca8231340ce7d65ef (diff) | |
| download | lwn-658fdbef66e5e9be79b457edc2cbbb3add840aa9.tar.gz lwn-658fdbef66e5e9be79b457edc2cbbb3add840aa9.zip | |
[PATCH] Don't leak NT bit into next task
SYSENTER can cause a NT to be set which might cause crashes on the IRET
in the next task.
Following similar i386 patch from Linus.
Signed-off-by: Andi Kleen <ak@suse.de>
| -rw-r--r-- | arch/x86_64/kernel/entry.S | 4 | ||||
| -rw-r--r-- | arch/x86_64/kernel/setup64.c | 4 | ||||
| -rw-r--r-- | include/asm-x86_64/system.h | 5 |
3 files changed, 11 insertions, 2 deletions
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S index 4cbc65290ae7..2802524104f3 100644 --- a/arch/x86_64/kernel/entry.S +++ b/arch/x86_64/kernel/entry.S @@ -155,6 +155,10 @@ /* rdi: prev */ ENTRY(ret_from_fork) CFI_DEFAULT_STACK + push kernel_eflags(%rip) + CFI_ADJUST_CFA_OFFSET 4 + popf # reset kernel eflags + CFI_ADJUST_CFA_OFFSET -4 call schedule_tail GET_THREAD_INFO(%rcx) testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT),threadinfo_flags(%rcx) diff --git a/arch/x86_64/kernel/setup64.c b/arch/x86_64/kernel/setup64.c index 9332d2361e08..8c4b80fe71a1 100644 --- a/arch/x86_64/kernel/setup64.c +++ b/arch/x86_64/kernel/setup64.c @@ -180,6 +180,8 @@ void __cpuinit check_efer(void) } } +unsigned long kernel_eflags; + /* * cpu_init() initializes state that is per-CPU. Some data is already * initialized (naturally) in the bootstrap process, such as the GDT @@ -281,4 +283,6 @@ void __cpuinit cpu_init (void) set_debugreg(0UL, 7); fpu_init(); + + raw_local_save_flags(kernel_eflags); } diff --git a/include/asm-x86_64/system.h b/include/asm-x86_64/system.h index 6bf170bceae1..bd376bc8c4ab 100644 --- a/include/asm-x86_64/system.h +++ b/include/asm-x86_64/system.h @@ -14,12 +14,13 @@ #define __RESTORE(reg,offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t" /* frame pointer must be last for get_wchan */ -#define SAVE_CONTEXT "pushq %%rbp ; movq %%rsi,%%rbp\n\t" -#define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp\n\t" +#define SAVE_CONTEXT "pushf ; pushq %%rbp ; movq %%rsi,%%rbp\n\t" +#define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp ; popf\t" #define __EXTRA_CLOBBER \ ,"rcx","rbx","rdx","r8","r9","r10","r11","r12","r13","r14","r15" +/* Save restore flags to clear handle leaking NT */ #define switch_to(prev,next,last) \ asm volatile(SAVE_CONTEXT \ "movq %%rsp,%P[threadrsp](%[prev])\n\t" /* save RSP */ \ |