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lkdtm/stackleak: check stack boundaries

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The stackleak code relies upon the current SP and lowest recorded SP
falling within expected task stack boundaries.

Check this at the start of the test.

Signed-off-by: Mark Rutland <[email protected]>
Cc: Alexander Popov <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
This commit is contained in:
Mark Rutland authored and Kees Cook committed 2022-05-08 01:33:09 -07:00
1 parent f03a50938d
commit f171d695f3
1 file changed
+20
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drivers/misc/lkdtm/stackleak.c
+20
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@@ -35,6 +35,25 @@ static void noinstr check_stackleak_irqoff(void)
unsigned long poison_high, poison_low;
bool test_failed = false;
/*
* Check that the current and lowest recorded stack pointer values fall
* within the expected task stack boundaries. These tests should never
* fail unless the boundaries are incorrect or we're clobbering the
* STACK_END_MAGIC, and in either casee something is seriously wrong.
*/
if (current_sp < task_stack_low || current_sp >= task_stack_high) {
pr_err("FAIL: current_stack_pointer (0x%lx) outside of task stack bounds [0x%lx..0x%lx]\n",
current_sp, task_stack_low, task_stack_high - 1);
test_failed = true;
goto out;
}
if (lowest_sp < task_stack_low || lowest_sp >= task_stack_high) {
pr_err("FAIL: current->lowest_stack (0x%lx) outside of task stack bounds [0x%lx..0x%lx]\n",
lowest_sp, task_stack_low, task_stack_high - 1);
test_failed = true;
goto out;
}
/*
* Depending on what has run prior to this test, the lowest recorded
* stack pointer could be above or below the current stack pointer.
@@ -87,6 +106,7 @@ static void noinstr check_stackleak_irqoff(void)
poison_high - task_stack_low,
task_stack_low - task_stack_base);
out:
if (test_failed) {
pr_err("FAIL: the thread stack is NOT properly erased!\n");
pr_expected_config(CONFIG_GCC_PLUGIN_STACKLEAK);