From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>, x86 <x86@kernel.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH] lkdtm/bugs: Avoid ifdefs for DOUBLE_FAULT
Date: Wed, 27 Nov 2019 11:19:20 -0800 [thread overview]
Message-ID: <201911271118.FCC2D04F@keescook> (raw)
LKDTM test visibility shouldn't change, so remove the ifdefs on
DOUBLE_FAULT and make sure test failure doesn't crash the system.
Link: https://lore.kernel.org/lkml/20191127184837.GA35982@gmail.com
Fixes: b09511c253e5 ("lkdtm: Add a DOUBLE_FAULT crash type on x86")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
applies on top of tip/x86/urgent
---
drivers/misc/lkdtm/bugs.c | 8 +++++---
drivers/misc/lkdtm/core.c | 4 +---
drivers/misc/lkdtm/lkdtm.h | 2 --
3 files changed, 6 insertions(+), 8 deletions(-)
diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index a4fdad04809a..22f5293414cc 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -342,9 +342,9 @@ void lkdtm_UNSET_SMEP(void)
#endif
}
-#ifdef CONFIG_X86_32
void lkdtm_DOUBLE_FAULT(void)
{
+#ifdef CONFIG_X86_32
/*
* Trigger #DF by setting the stack limit to zero. This clobbers
* a GDT TLS slot, which is okay because the current task will die
@@ -373,6 +373,8 @@ void lkdtm_DOUBLE_FAULT(void)
asm volatile ("movw %0, %%ss; addl $0, (%%esp)" ::
"r" ((unsigned short)(GDT_ENTRY_TLS_MIN << 3)));
- panic("tried to double fault but didn't die\n");
-}
+ pr_err("FAIL: tried to double fault but didn't die!\n");
+#else
+ pr_err("FAIL: this test is only available on 32-bit x86.\n");
#endif
+}
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index ee0d6e721441..7082ef8a2b99 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -116,6 +116,7 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(STACK_GUARD_PAGE_LEADING),
CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
CRASHTYPE(UNSET_SMEP),
+ CRASHTYPE(DOUBLE_FAULT),
CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
CRASHTYPE(OVERWRITE_ALLOCATION),
CRASHTYPE(WRITE_AFTER_FREE),
@@ -171,9 +172,6 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(USERCOPY_KERNEL_DS),
CRASHTYPE(STACKLEAK_ERASING),
CRASHTYPE(CFI_FORWARD_PROTO),
-#ifdef CONFIG_X86_32
- CRASHTYPE(DOUBLE_FAULT),
-#endif
};
diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index c56d23e37643..f4952efd6785 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/drivers/misc/lkdtm/lkdtm.h
@@ -28,9 +28,7 @@ void lkdtm_CORRUPT_USER_DS(void);
void lkdtm_STACK_GUARD_PAGE_LEADING(void);
void lkdtm_STACK_GUARD_PAGE_TRAILING(void);
void lkdtm_UNSET_SMEP(void);
-#ifdef CONFIG_X86_32
void lkdtm_DOUBLE_FAULT(void);
-#endif
/* lkdtm_heap.c */
void __init lkdtm_heap_init(void);
--
2.17.1
--
Kees Cook
next reply other threads:[~2019-11-27 19:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 19:19 Kees Cook [this message]
2019-11-27 21:01 ` [PATCH] lkdtm/bugs: Avoid ifdefs for DOUBLE_FAULT Andy Lutomirski
2019-11-28 1:50 ` Kees Cook
2019-11-28 2:15 ` Andy Lutomirski
2019-11-28 2:54 ` Kees Cook
2019-11-28 3:48 ` Andy Lutomirski
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