* [PATCH 4.14 57/75] locking/refcounts, x86/asm: Use unique .text section for refcount exceptions
[not found] <20171207130818.742746317@linuxfoundation.org>
@ 2017-12-07 13:08 ` Greg Kroah-Hartman
2017-12-07 13:08 ` Greg Kroah-Hartman
2017-12-07 13:08 ` [PATCH 4.14 64/75] locking/refcounts, x86/asm: Enable CONFIG_ARCH_HAS_REFCOUNT Greg Kroah-Hartman
1 sibling, 1 reply; 4+ messages in thread
From: Greg Kroah-Hartman @ 2017-12-07 13:08 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Mike Galbraith, Kees Cook,
Ard Biesheuvel, Elena, Linus Torvalds, Peter Zijlstra,
Thomas Gleixner, linux-arch, Ingo Molnar, Sasha Levin
4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook <keescook@chromium.org>
[ Upstream commit 564c9cc84e2adf8a6671c1937f0a9fe3da2a4b0e ]
Using .text.unlikely for refcount exceptions isn't safe because gcc may
move entire functions into .text.unlikely (e.g. in6_dev_dev()), which
would cause any uses of a protected refcount_t function to stay inline
with the function, triggering the protection unconditionally:
.section .text.unlikely,"ax",@progbits
.type in6_dev_get, @function
in6_dev_getx:
.LFB4673:
.loc 2 4128 0
.cfi_startproc
...
lock; incl 480(%rbx)
js 111f
.pushsection .text.unlikely
111: lea 480(%rbx), %rcx
112: .byte 0x0f, 0xff
.popsection
113:
This creates a unique .text..refcount section and adds an additional
test to the exception handler to WARN in the case of having none of OF,
SF, nor ZF set so we can see things like this more easily in the future.
The double dot for the section name keeps it out of the TEXT_MAIN macro
namespace, to avoid collisions and so it can be put at the end with
text.unlikely to keep the cold code together.
See commit:
cb87481ee89db ("kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured")
... which matches C names: [a-zA-Z0-9_] but not ".".
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Elena <elena.reshetova@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch <linux-arch@vger.kernel.org>
Fixes: 7a46ec0e2f48 ("locking/refcounts, x86/asm: Implement fast refcount overflow protection")
Link: http://lkml.kernel.org/r/1504382986-49301-2-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/refcount.h | 2 +-
arch/x86/mm/extable.c | 7 ++++++-
include/asm-generic/vmlinux.lds.h | 1 +
3 files changed, 8 insertions(+), 2 deletions(-)
--- a/arch/x86/include/asm/refcount.h
+++ b/arch/x86/include/asm/refcount.h
@@ -15,7 +15,7 @@
* back to the regular execution flow in .text.
*/
#define _REFCOUNT_EXCEPTION \
- ".pushsection .text.unlikely\n" \
+ ".pushsection .text..refcount\n" \
"111:\tlea %[counter], %%" _ASM_CX "\n" \
"112:\t" ASM_UD0 "\n" \
ASM_UNREACHABLE \
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -67,12 +67,17 @@ bool ex_handler_refcount(const struct ex
* wrapped around) will be set. Additionally, seeing the refcount
* reach 0 will set ZF (Zero Flag: result was zero). In each of
* these cases we want a report, since it's a boundary condition.
- *
+ * The SF case is not reported since it indicates post-boundary
+ * manipulations below zero or above INT_MAX. And if none of the
+ * flags are set, something has gone very wrong, so report it.
*/
if (regs->flags & (X86_EFLAGS_OF | X86_EFLAGS_ZF)) {
bool zero = regs->flags & X86_EFLAGS_ZF;
refcount_error_report(regs, zero ? "hit zero" : "overflow");
+ } else if ((regs->flags & X86_EFLAGS_SF) == 0) {
+ /* Report if none of OF, ZF, nor SF are set. */
+ refcount_error_report(regs, "unexpected saturation");
}
return true;
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -459,6 +459,7 @@
#define TEXT_TEXT \
ALIGN_FUNCTION(); \
*(.text.hot TEXT_MAIN .text.fixup .text.unlikely) \
+ *(.text..refcount) \
*(.ref.text) \
MEM_KEEP(init.text) \
MEM_KEEP(exit.text) \
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 4.14 57/75] locking/refcounts, x86/asm: Use unique .text section for refcount exceptions
2017-12-07 13:08 ` [PATCH 4.14 57/75] locking/refcounts, x86/asm: Use unique .text section for refcount exceptions Greg Kroah-Hartman
@ 2017-12-07 13:08 ` Greg Kroah-Hartman
0 siblings, 0 replies; 4+ messages in thread
From: Greg Kroah-Hartman @ 2017-12-07 13:08 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Mike Galbraith, Kees Cook,
Ard Biesheuvel, Elena, Linus Torvalds, Peter Zijlstra,
Thomas Gleixner, linux-arch, Ingo Molnar, Sasha Levin
4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook <keescook@chromium.org>
[ Upstream commit 564c9cc84e2adf8a6671c1937f0a9fe3da2a4b0e ]
Using .text.unlikely for refcount exceptions isn't safe because gcc may
move entire functions into .text.unlikely (e.g. in6_dev_dev()), which
would cause any uses of a protected refcount_t function to stay inline
with the function, triggering the protection unconditionally:
.section .text.unlikely,"ax",@progbits
.type in6_dev_get, @function
in6_dev_getx:
.LFB4673:
.loc 2 4128 0
.cfi_startproc
...
lock; incl 480(%rbx)
js 111f
.pushsection .text.unlikely
111: lea 480(%rbx), %rcx
112: .byte 0x0f, 0xff
.popsection
113:
This creates a unique .text..refcount section and adds an additional
test to the exception handler to WARN in the case of having none of OF,
SF, nor ZF set so we can see things like this more easily in the future.
The double dot for the section name keeps it out of the TEXT_MAIN macro
namespace, to avoid collisions and so it can be put at the end with
text.unlikely to keep the cold code together.
See commit:
cb87481ee89db ("kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured")
... which matches C names: [a-zA-Z0-9_] but not ".".
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Elena <elena.reshetova@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch <linux-arch@vger.kernel.org>
Fixes: 7a46ec0e2f48 ("locking/refcounts, x86/asm: Implement fast refcount overflow protection")
Link: http://lkml.kernel.org/r/1504382986-49301-2-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/refcount.h | 2 +-
arch/x86/mm/extable.c | 7 ++++++-
include/asm-generic/vmlinux.lds.h | 1 +
3 files changed, 8 insertions(+), 2 deletions(-)
--- a/arch/x86/include/asm/refcount.h
+++ b/arch/x86/include/asm/refcount.h
@@ -15,7 +15,7 @@
* back to the regular execution flow in .text.
*/
#define _REFCOUNT_EXCEPTION \
- ".pushsection .text.unlikely\n" \
+ ".pushsection .text..refcount\n" \
"111:\tlea %[counter], %%" _ASM_CX "\n" \
"112:\t" ASM_UD0 "\n" \
ASM_UNREACHABLE \
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -67,12 +67,17 @@ bool ex_handler_refcount(const struct ex
* wrapped around) will be set. Additionally, seeing the refcount
* reach 0 will set ZF (Zero Flag: result was zero). In each of
* these cases we want a report, since it's a boundary condition.
- *
+ * The SF case is not reported since it indicates post-boundary
+ * manipulations below zero or above INT_MAX. And if none of the
+ * flags are set, something has gone very wrong, so report it.
*/
if (regs->flags & (X86_EFLAGS_OF | X86_EFLAGS_ZF)) {
bool zero = regs->flags & X86_EFLAGS_ZF;
refcount_error_report(regs, zero ? "hit zero" : "overflow");
+ } else if ((regs->flags & X86_EFLAGS_SF) == 0) {
+ /* Report if none of OF, ZF, nor SF are set. */
+ refcount_error_report(regs, "unexpected saturation");
}
return true;
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -459,6 +459,7 @@
#define TEXT_TEXT \
ALIGN_FUNCTION(); \
*(.text.hot TEXT_MAIN .text.fixup .text.unlikely) \
+ *(.text..refcount) \
*(.ref.text) \
MEM_KEEP(init.text) \
MEM_KEEP(exit.text) \
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 4.14 64/75] locking/refcounts, x86/asm: Enable CONFIG_ARCH_HAS_REFCOUNT
[not found] <20171207130818.742746317@linuxfoundation.org>
2017-12-07 13:08 ` [PATCH 4.14 57/75] locking/refcounts, x86/asm: Use unique .text section for refcount exceptions Greg Kroah-Hartman
@ 2017-12-07 13:08 ` Greg Kroah-Hartman
2017-12-07 13:08 ` Greg Kroah-Hartman
1 sibling, 1 reply; 4+ messages in thread
From: Greg Kroah-Hartman @ 2017-12-07 13:08 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Kees Cook, Ard Biesheuvel, Elena,
Linus Torvalds, Mike Galbraith, Peter Zijlstra, Thomas Gleixner,
linux-arch, Ingo Molnar, Sasha Levin
4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook <keescook@chromium.org>
[ Upstream commit 39208aa7ecb7d9c4e86df782b5693270313cbab1 ]
With the section inlining bug fixed for the x86 refcount protection,
we can turn the config back on.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Elena <elena.reshetova@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch <linux-arch@vger.kernel.org>
Link: http://lkml.kernel.org/r/1504382986-49301-3-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -56,7 +56,7 @@ config X86
select ARCH_HAS_KCOV if X86_64
select ARCH_HAS_PMEM_API if X86_64
# Causing hangs/crashes, see the commit that added this change for details.
- select ARCH_HAS_REFCOUNT if BROKEN
+ select ARCH_HAS_REFCOUNT
select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_SG_CHAIN
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 4.14 64/75] locking/refcounts, x86/asm: Enable CONFIG_ARCH_HAS_REFCOUNT
2017-12-07 13:08 ` [PATCH 4.14 64/75] locking/refcounts, x86/asm: Enable CONFIG_ARCH_HAS_REFCOUNT Greg Kroah-Hartman
@ 2017-12-07 13:08 ` Greg Kroah-Hartman
0 siblings, 0 replies; 4+ messages in thread
From: Greg Kroah-Hartman @ 2017-12-07 13:08 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Kees Cook, Ard Biesheuvel, Elena,
Linus Torvalds, Mike Galbraith, Peter Zijlstra, Thomas Gleixner,
linux-arch, Ingo Molnar, Sasha Levin
4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook <keescook@chromium.org>
[ Upstream commit 39208aa7ecb7d9c4e86df782b5693270313cbab1 ]
With the section inlining bug fixed for the x86 refcount protection,
we can turn the config back on.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Elena <elena.reshetova@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch <linux-arch@vger.kernel.org>
Link: http://lkml.kernel.org/r/1504382986-49301-3-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -56,7 +56,7 @@ config X86
select ARCH_HAS_KCOV if X86_64
select ARCH_HAS_PMEM_API if X86_64
# Causing hangs/crashes, see the commit that added this change for details.
- select ARCH_HAS_REFCOUNT if BROKEN
+ select ARCH_HAS_REFCOUNT
select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_SG_CHAIN
^ permalink raw reply [flat|nested] 4+ messages in thread
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[not found] <20171207130818.742746317@linuxfoundation.org>
2017-12-07 13:08 ` [PATCH 4.14 57/75] locking/refcounts, x86/asm: Use unique .text section for refcount exceptions Greg Kroah-Hartman
2017-12-07 13:08 ` Greg Kroah-Hartman
2017-12-07 13:08 ` [PATCH 4.14 64/75] locking/refcounts, x86/asm: Enable CONFIG_ARCH_HAS_REFCOUNT Greg Kroah-Hartman
2017-12-07 13:08 ` Greg Kroah-Hartman
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