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SubjectRe: [PATCH v1 1/1] lkdtm/stackleak: Make the stack erasing test more verbose
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Hello!

Just a friendly ping.
Could I have the feedback for this patch?

Best regards,
Alexander


On 19.12.2019 17:54, Alexander Popov wrote:
> Make the stack erasing test more verbose about the errors that it
> can detect. BUG() in case of test failure is useful when the test
> is running in a loop.
>
> Signed-off-by: Alexander Popov <alex.popov@linux.com>
> ---
> drivers/misc/lkdtm/stackleak.c | 25 +++++++++++++++++--------
> 1 file changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/misc/lkdtm/stackleak.c b/drivers/misc/lkdtm/stackleak.c
> index d5a084475abc..d198de4d4c7e 100644
> --- a/drivers/misc/lkdtm/stackleak.c
> +++ b/drivers/misc/lkdtm/stackleak.c
> @@ -16,6 +16,7 @@ void lkdtm_STACKLEAK_ERASING(void)
> unsigned long *sp, left, found, i;
> const unsigned long check_depth =
> STACKLEAK_SEARCH_DEPTH / sizeof(unsigned long);
> + bool test_failed = false;
>
> /*
> * For the details about the alignment of the poison values, see
> @@ -34,7 +35,8 @@ void lkdtm_STACKLEAK_ERASING(void)
> left--;
> } else {
> pr_err("FAIL: not enough stack space for the test\n");
> - return;
> + test_failed = true;
> + goto end;
> }
>
> pr_info("checking unused part of the thread stack (%lu bytes)...\n",
> @@ -52,22 +54,29 @@ void lkdtm_STACKLEAK_ERASING(void)
> }
>
> if (found <= check_depth) {
> - pr_err("FAIL: thread stack is not erased (checked %lu bytes)\n",
> + pr_err("FAIL: the erased part is not found (checked %lu bytes)\n",
> i * sizeof(unsigned long));
> - return;
> + test_failed = true;
> + goto end;
> }
>
> - pr_info("first %lu bytes are unpoisoned\n",
> + pr_info("the erased part begins after %lu not poisoned bytes\n",
> (i - found) * sizeof(unsigned long));
>
> /* The rest of thread stack should be erased */
> for (; i < left; i++) {
> if (*(sp - i) != STACKLEAK_POISON) {
> - pr_err("FAIL: thread stack is NOT properly erased\n");
> - return;
> + pr_err("FAIL: bad value number %lu in the erased part: 0x%lx\n",
> + i, *(sp - i));
> + test_failed = true;
> }
> }
>
> - pr_info("OK: the rest of the thread stack is properly erased\n");
> - return;
> +end:
> + if (test_failed) {
> + pr_err("FAIL: the thread stack is NOT properly erased\n");
> + BUG();
> + } else {
> + pr_info("OK: the rest of the thread stack is properly erased\n");
> + }
> }
>

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