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lkdtm/bugs: Make double-fault test always available

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Adjust the DOUBLE_FAULT test to always be available (so test harnesses
don't have to make exceptions more missing tests), and for the
arch-specific tests to "XFAIL" so that test harnesses can reason about
expected vs unexpected failures.

Fixes: b09511c253 ("lkdtm: Add a DOUBLE_FAULT crash type on x86")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/202001021226.751D3F869D@keescook
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kees Cook 2020-01-02 12:29:17 -08:00 • committed by Greg Kroah-Hartman
parent 500589d8bd
commit cea23efb4d
1 changed files with 6 additions and 4 deletions
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10
drivers/misc/lkdtm/bugs.c
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@ -338,13 +338,13 @@ void lkdtm_UNSET_SMEP(void)
native_write_cr4(cr4); native_write_cr4(cr4);
} }
#else #else
pr_err("FAIL: this test is x86_64-only\n"); pr_err("XFAIL: this test is x86_64-only\n");
#endif #endif
} }
#ifdef CONFIG_X86_32
void lkdtm_DOUBLE_FAULT(void) void lkdtm_DOUBLE_FAULT(void)
{ {
#ifdef CONFIG_X86_32
/* /*
* Trigger #DF by setting the stack limit to zero. This clobbers * Trigger #DF by setting the stack limit to zero. This clobbers
* a GDT TLS slot, which is okay because the current task will die * 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)" :: asm volatile ("movw %0, %%ss; addl $0, (%%esp)" ::
"r" ((unsigned short)(GDT_ENTRY_TLS_MIN << 3))); "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("XFAIL: this test is ia32-only\n");
#endif #endif
}