mirror of
https://github.com/torvalds/linux.git
synced 2024-11-25 13:41:51 +00:00
f90d1e0c78
Introduce an lkdtm test for the STACKLEAK feature: check that the current task stack is properly erased (filled with STACKLEAK_POISON). Signed-off-by: Alexander Popov <alex.popov@linux.com> Signed-off-by: Tycho Andersen <tycho@tycho.ws> Tested-by: Laura Abbott <labbott@redhat.com> Signed-off-by: Kees Cook <keescook@chromium.org>
74 lines
1.7 KiB
C
74 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* This code tests that the current task stack is properly erased (filled
|
|
* with STACKLEAK_POISON).
|
|
*
|
|
* Authors:
|
|
* Alexander Popov <alex.popov@linux.com>
|
|
* Tycho Andersen <tycho@tycho.ws>
|
|
*/
|
|
|
|
#include "lkdtm.h"
|
|
#include <linux/stackleak.h>
|
|
|
|
void lkdtm_STACKLEAK_ERASING(void)
|
|
{
|
|
unsigned long *sp, left, found, i;
|
|
const unsigned long check_depth =
|
|
STACKLEAK_SEARCH_DEPTH / sizeof(unsigned long);
|
|
|
|
/*
|
|
* For the details about the alignment of the poison values, see
|
|
* the comment in stackleak_track_stack().
|
|
*/
|
|
sp = PTR_ALIGN(&i, sizeof(unsigned long));
|
|
|
|
left = ((unsigned long)sp & (THREAD_SIZE - 1)) / sizeof(unsigned long);
|
|
sp--;
|
|
|
|
/*
|
|
* One 'long int' at the bottom of the thread stack is reserved
|
|
* and not poisoned.
|
|
*/
|
|
if (left > 1) {
|
|
left--;
|
|
} else {
|
|
pr_err("FAIL: not enough stack space for the test\n");
|
|
return;
|
|
}
|
|
|
|
pr_info("checking unused part of the thread stack (%lu bytes)...\n",
|
|
left * sizeof(unsigned long));
|
|
|
|
/*
|
|
* Search for 'check_depth' poison values in a row (just like
|
|
* stackleak_erase() does).
|
|
*/
|
|
for (i = 0, found = 0; i < left && found <= check_depth; i++) {
|
|
if (*(sp - i) == STACKLEAK_POISON)
|
|
found++;
|
|
else
|
|
found = 0;
|
|
}
|
|
|
|
if (found <= check_depth) {
|
|
pr_err("FAIL: thread stack is not erased (checked %lu bytes)\n",
|
|
i * sizeof(unsigned long));
|
|
return;
|
|
}
|
|
|
|
pr_info("first %lu bytes are unpoisoned\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_info("OK: the rest of the thread stack is properly erased\n");
|
|
return;
|
|
}
|