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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id w5sm17977385pfd.31.2019.11.27.11.19.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Nov 2019 11:19:21 -0800 (PST) Date: Wed, 27 Nov 2019 11:19:20 -0800 From: Kees Cook To: Ingo Molnar Cc: Andy Lutomirski , x86 , linux-kernel@vger.kernel.org Subject: [PATCH] lkdtm/bugs: Avoid ifdefs for DOUBLE_FAULT Message-ID: <201911271118.FCC2D04F@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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