2018-06-27 05:56:14

by Andy Lutomirski

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

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.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: [email protected]
Fixes: 8bb2610bc496 ("x86/entry/64/compat: Preserve r8-r11 in int $0x80")
Cc: [email protected]
Signed-off-by: Andy Lutomirski <[email protected]>
---
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 */
--
2.17.1

2018-06-27 08:52:37

by Li Zhijian

Subject: Re: [PATCH] x86/entry/64/compat: Fix "x86/entry/64/compat: Preserve r8-r11 in int $0x80"

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.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: [email protected]
> Fixes: 8bb2610bc496 ("x86/entry/64/compat: Preserve r8-r11 in int $0x80")
> Cc: [email protected]
> Signed-off-by: Andy Lutomirski <[email protected]>

Tested-by: Li Zhijian <[email protected]>


> ---
> 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 */

2018-06-27 09:09:42

by tip-bot for Vasyl Gomonovych

Subject: [tip:x86/urgent] x86/entry/64/compat: Fix "x86/entry/64/compat: Preserve r8-r11 in int $0x80"

Commit-ID: 22cd978e598618e82c3c3348d2069184f6884182
Gitweb: https://git.kernel.org/tip/22cd978e598618e82c3c3348d2069184f6884182
Author: Andy Lutomirski <[email protected]>
AuthorDate: Tue, 26 Jun 2018 22:45:52 -0700
Committer: Ingo Molnar <[email protected]>
CommitDate: Wed, 27 Jun 2018 09:35:40 +0200

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

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: [email protected]
Signed-off-by: Andy Lutomirski <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected] #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 <[email protected]>
---
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 */