x86/entry/64/compat: Fix "x86/entry/64/compat: Preserve r8-r11 in int $0x80"

commit 22cd978e598618e82c3c3348d2069184f6884182 upstream.

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, but "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.1523975710.git.luto@kernel.org/raw

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
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org #v4.17+
Fixes: 8bb2610bc496 ("x86/entry/64/compat: Preserve r8-r11 in int $0x80")
Link: http://lkml.kernel.org/r/6012b922485401bc42676e804171ded262fc2ef2.1530078306.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Alistair Delva <adelva@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 96628968858bd12154d78766ce70c358966a4ca9..304e3daf82dd25c6daa96b63bf30cd350f3c36bb 100644 (file)
--- 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 */
@@ -357,13 +357,13 @@ ENTRY(entry_INT80_compat)
        pushq   %rdx                    /* pt_regs->dx */
        pushq   %rcx                    /* pt_regs->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 */