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author | Mark Rutland <mark.rutland@arm.com> | 2022-05-06 15:11:45 +0300 |
---|---|---|
committer | Kees Cook <keescook@chromium.org> | 2022-05-08 11:33:09 +0300 |
commit | 8c6a490e404fe82b53bbafe0f0eeef10605617f7 (patch) | |
tree | 7a8e5fe60a10ebe53fdb8df023d2933abe867ae9 /drivers/misc/lkdtm/stackleak.c | |
parent | 88959a39a1708fc755a89923d60e50de74847bc9 (diff) | |
download | linux-8c6a490e404fe82b53bbafe0f0eeef10605617f7.tar.xz |
lkdtm/stackleak: fix CONFIG_GCC_PLUGIN_STACKLEAK=n
Recent rework broke building LKDTM when CONFIG_GCC_PLUGIN_STACKLEAK=n.
This patch fixes that breakage.
Prior to recent stackleak rework, the LKDTM STACKLEAK_ERASING code could
be built when the kernel was not built with stackleak support, and would
run a test that would almost certainly fail (or pass by sheer cosmic
coincidence), e.g.
| # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT
| lkdtm: Performing direct entry STACKLEAK_ERASING
| lkdtm: checking unused part of the thread stack (15560 bytes)...
| lkdtm: FAIL: the erased part is not found (checked 15560 bytes)
| lkdtm: FAIL: the thread stack is NOT properly erased!
| lkdtm: This is probably expected, since this kernel (5.18.0-rc2 aarch64) was built *without* CONFIG_GCC_PLUGIN_STACKLEAK=y
The recent rework to the test made it more accurate by using helpers
which are only defined when CONFIG_GCC_PLUGIN_STACKLEAK=y, and so when
building LKDTM when CONFIG_GCC_PLUGIN_STACKLEAK=n, we get a build
failure:
| drivers/misc/lkdtm/stackleak.c: In function 'check_stackleak_irqoff':
| drivers/misc/lkdtm/stackleak.c:30:46: error: implicit declaration of function 'stackleak_task_low_bound' [-Werror=implicit-function-declaration]
| 30 | const unsigned long task_stack_low = stackleak_task_low_bound(current);
| | ^~~~~~~~~~~~~~~~~~~~~~~~
| drivers/misc/lkdtm/stackleak.c:31:47: error: implicit declaration of function 'stackleak_task_high_bound'; did you mean 'stackleak_task_init'? [-Werror=implicit-function-declaration]
| 31 | const unsigned long task_stack_high = stackleak_task_high_bound(current);
| | ^~~~~~~~~~~~~~~~~~~~~~~~~
| | stackleak_task_init
| drivers/misc/lkdtm/stackleak.c:33:48: error: 'struct task_struct' has no member named 'lowest_stack'
| 33 | const unsigned long lowest_sp = current->lowest_stack;
| | ^~
| drivers/misc/lkdtm/stackleak.c:74:23: error: implicit declaration of function 'stackleak_find_top_of_poison' [-Werror=implicit-function-declaration]
| 74 | poison_high = stackleak_find_top_of_poison(task_stack_low, untracked_high);
| | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
This patch fixes the issue by not compiling the body of the test when
CONFIG_GCC_PLUGIN_STACKLEAK=n, and replacing this with an unconditional
XFAIL message. This means the pr_expected_config() in
check_stackleak_irqoff() is redundant, and so it is removed.
Where an architecture does not support stackleak, the test will log:
| # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT
| lkdtm: Performing direct entry STACKLEAK_ERASING
| lkdtm: XFAIL: stackleak is not supported on this arch (HAVE_ARCH_STACKLEAK=n)
Where an architectures does support stackleak, but this has not been
compiled in, the test will log:
| # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT
| lkdtm: Performing direct entry STACKLEAK_ERASING
| lkdtm: XFAIL: stackleak is not enabled (CONFIG_GCC_PLUGIN_STACKLEAK=n)
Where stackleak has been compiled in, the test behaves as usual:
| # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT
| lkdtm: Performing direct entry STACKLEAK_ERASING
| lkdtm: stackleak stack usage:
| high offset: 336 bytes
| current: 688 bytes
| lowest: 1232 bytes
| tracked: 1232 bytes
| untracked: 672 bytes
| poisoned: 14136 bytes
| low offset: 8 bytes
| lkdtm: OK: the rest of the thread stack is properly erased
Fixes: f4cfacd92972cc44 ("lkdtm/stackleak: rework boundary management")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Popov <alex.popov@linux.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220506121145.1162908-1-mark.rutland@arm.com
Diffstat (limited to 'drivers/misc/lkdtm/stackleak.c')
-rw-r--r-- | drivers/misc/lkdtm/stackleak.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/misc/lkdtm/stackleak.c b/drivers/misc/lkdtm/stackleak.c index 52800583fd05..82369c6f889e 100644 --- a/drivers/misc/lkdtm/stackleak.c +++ b/drivers/misc/lkdtm/stackleak.c @@ -11,6 +11,7 @@ #include "lkdtm.h" #include <linux/stackleak.h> +#if defined(CONFIG_GCC_PLUGIN_STACKLEAK) /* * Check that stackleak tracks the lowest stack pointer and erases the stack * below this as expected. @@ -109,7 +110,6 @@ static void noinstr check_stackleak_irqoff(void) out: if (test_failed) { pr_err("FAIL: the thread stack is NOT properly erased!\n"); - pr_expected_config(CONFIG_GCC_PLUGIN_STACKLEAK); } else { pr_info("OK: the rest of the thread stack is properly erased\n"); } @@ -123,3 +123,13 @@ void lkdtm_STACKLEAK_ERASING(void) check_stackleak_irqoff(); local_irq_restore(flags); } +#else /* defined(CONFIG_GCC_PLUGIN_STACKLEAK) */ +void lkdtm_STACKLEAK_ERASING(void) +{ + if (IS_ENABLED(CONFIG_HAVE_ARCH_STACKLEAK)) { + pr_err("XFAIL: stackleak is not enabled (CONFIG_GCC_PLUGIN_STACKLEAK=n)\n"); + } else { + pr_err("XFAIL: stackleak is not supported on this arch (HAVE_ARCH_STACKLEAK=n)\n"); + } +} +#endif /* defined(CONFIG_GCC_PLUGIN_STACKLEAK) */ |