On 6/27/2018 1:45 PM, Andy Lutomirski wrote:

Commit 8bb2610bc496 ("x86/entry/64/compat: Preserve r8-r11 in int $0x80") was busted. My original patch had a minor conflict with some of the nospec changes. git apply is very clever and silently accepted the patch by making the same changes to a different function in the same file. There was obviously a huge offset, but git apply for some reason doesn't feel any need to say so.

Move the changes to the correct function. Now the test_syscall_vdso_32 selftests passes.

If anyone cares to observe the original problem, try applying the patch at https://lore.kernel.org/lkml/d4c4d9985fbe64f8c9e19291886453914b48caee.152397... to the kernel at 316d097c4cd4e7f2ef50c40cff2db266593c4ec4. git am and git apply accept the patch without any complaints at all. patch -p1 at least prints out a message about the huge offset.

Reported-by: zhijianx.li@intel.com Fixes: 8bb2610bc496 ("x86/entry/64/compat: Preserve r8-r11 in int $0x80") Cc: stable@vger.kernel.org Signed-off-by: Andy Lutomirski luto@kernel.org

Tested-by: Li Zhijian zhijianx.li@intel.com

---

arch/x86/entry/entry_64_compat.S | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index 9de7f1e1dede..7d0df78db727 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -84,13 +84,13 @@ ENTRY(entry_SYSENTER_compat) pushq %rdx /* pt_regs->dx */ pushq %rcx /* pt_regs->cx */ pushq $-ENOSYS /* pt_regs->ax */

• pushq %r8 /* pt_regs->r8 */

• pushq $0 /* pt_regs->r8 = 0 */ xorl %r8d, %r8d /* nospec r8 */

• pushq %r9 /* pt_regs->r9 */

• pushq $0 /* pt_regs->r9 = 0 */ xorl %r9d, %r9d /* nospec r9 */

• pushq %r10 /* pt_regs->r10 */

• pushq $0 /* pt_regs->r10 = 0 */ xorl %r10d, %r10d /* nospec r10 */

• pushq %r11 /* pt_regs->r11 */

• pushq $0 /* pt_regs->r11 = 0 */ xorl %r11d, %r11d /* nospec r11 */ pushq %rbx /* pt_regs->rbx */ xorl %ebx, %ebx /* nospec rbx */

@@ -374,13 +374,13 @@ ENTRY(entry_INT80_compat) pushq %rcx /* pt_regs->cx */ xorl %ecx, %ecx /* nospec cx */ pushq $-ENOSYS /* pt_regs->ax */

• pushq $0 /* pt_regs->r8 = 0 */

• pushq %r8 /* pt_regs->r8 */ xorl %r8d, %r8d /* nospec r8 */

• pushq $0 /* pt_regs->r9 = 0 */

• pushq %r9 /* pt_regs->r9 */ xorl %r9d, %r9d /* nospec r9 */

• pushq $0 /* pt_regs->r10 = 0 */

• pushq %r10 /* pt_regs->r10*/ xorl %r10d, %r10d /* nospec r10 */

• pushq $0 /* pt_regs->r11 = 0 */

• pushq %r11 /* pt_regs->r11 */ xorl %r11d, %r11d /* nospec r11 */ pushq %rbx /* pt_regs->rbx */ xorl %ebx, %ebx /* nospec rbx */