From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- drivers/misc/lkdtm/stackleak.c | 150 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 drivers/misc/lkdtm/stackleak.c (limited to 'drivers/misc/lkdtm/stackleak.c') diff --git a/drivers/misc/lkdtm/stackleak.c b/drivers/misc/lkdtm/stackleak.c new file mode 100644 index 0000000000..f1d0221609 --- /dev/null +++ b/drivers/misc/lkdtm/stackleak.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This code tests that the current task stack is properly erased (filled + * with STACKLEAK_POISON). + * + * Authors: + * Alexander Popov + * Tycho Andersen + */ + +#include "lkdtm.h" +#include + +#if defined(CONFIG_GCC_PLUGIN_STACKLEAK) +/* + * Check that stackleak tracks the lowest stack pointer and erases the stack + * below this as expected. + * + * To prevent the lowest stack pointer changing during the test, IRQs are + * masked and instrumentation of this function is disabled. We assume that the + * compiler will create a fixed-size stack frame for this function. + * + * Any non-inlined function may make further use of the stack, altering the + * lowest stack pointer and/or clobbering poison values. To avoid spurious + * failures we must avoid printing until the end of the test or have already + * encountered a failure condition. + */ +static void noinstr check_stackleak_irqoff(void) +{ + const unsigned long task_stack_base = (unsigned long)task_stack_page(current); + const unsigned long task_stack_low = stackleak_task_low_bound(current); + const unsigned long task_stack_high = stackleak_task_high_bound(current); + const unsigned long current_sp = current_stack_pointer; + const unsigned long lowest_sp = current->lowest_stack; + unsigned long untracked_high; + 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) { + instrumentation_begin(); + 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) { + instrumentation_begin(); + 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. + * Start from the lowest of the two. + * + * Poison values are naturally-aligned unsigned longs. As the current + * stack pointer might not be sufficiently aligned, we must align + * downwards to find the lowest known stack pointer value. This is the + * high boundary for a portion of the stack which may have been used + * without being tracked, and has to be scanned for poison. + */ + untracked_high = min(current_sp, lowest_sp); + untracked_high = ALIGN_DOWN(untracked_high, sizeof(unsigned long)); + + /* + * Find the top of the poison in the same way as the erasing code. + */ + poison_high = stackleak_find_top_of_poison(task_stack_low, untracked_high); + + /* + * Check whether the poisoned portion of the stack (if any) consists + * entirely of poison. This verifies the entries that + * stackleak_find_top_of_poison() should have checked. + */ + poison_low = poison_high; + while (poison_low > task_stack_low) { + poison_low -= sizeof(unsigned long); + + if (*(unsigned long *)poison_low == STACKLEAK_POISON) + continue; + + instrumentation_begin(); + pr_err("FAIL: non-poison value %lu bytes below poison boundary: 0x%lx\n", + poison_high - poison_low, *(unsigned long *)poison_low); + test_failed = true; + goto out; + } + + instrumentation_begin(); + pr_info("stackleak stack usage:\n" + " high offset: %lu bytes\n" + " current: %lu bytes\n" + " lowest: %lu bytes\n" + " tracked: %lu bytes\n" + " untracked: %lu bytes\n" + " poisoned: %lu bytes\n" + " low offset: %lu bytes\n", + task_stack_base + THREAD_SIZE - task_stack_high, + task_stack_high - current_sp, + task_stack_high - lowest_sp, + task_stack_high - untracked_high, + untracked_high - poison_high, + 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"); + } else { + pr_info("OK: the rest of the thread stack is properly erased\n"); + } + instrumentation_end(); +} + +static void lkdtm_STACKLEAK_ERASING(void) +{ + unsigned long flags; + + local_irq_save(flags); + check_stackleak_irqoff(); + local_irq_restore(flags); +} +#else /* defined(CONFIG_GCC_PLUGIN_STACKLEAK) */ +static 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) */ + +static struct crashtype crashtypes[] = { + CRASHTYPE(STACKLEAK_ERASING), +}; + +struct crashtype_category stackleak_crashtypes = { + .crashtypes = crashtypes, + .len = ARRAY_SIZE(crashtypes), +}; -- cgit v1.2.3