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linux/drivers/misc/lkdtm/bugs.c

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 22:07:57 +08:00
// SPDX-License-Identifier: GPL-2.0
/*
* This is for all the tests related to logic bugs (e.g. bad dereferences,
* bad alignment, bad loops, bad locking, bad scheduling, deep stacks, and
* lockups) along with other things that don't fit well into existing LKDTM
* test source files.
*/
#include "lkdtm.h"
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
#include <linux/sched/task_stack.h>
#include <linux/uaccess.h>
struct lkdtm_list {
struct list_head node;
};
/*
* Make sure our attempts to over run the kernel stack doesn't trigger
* a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
* recurse past the end of THREAD_SIZE by default.
*/
#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
#else
#define REC_STACK_SIZE (THREAD_SIZE / 8)
#endif
#define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
static int recur_count = REC_NUM_DEFAULT;
static DEFINE_SPINLOCK(lock_me_up);
/*
* Make sure compiler does not optimize this function or stack frame away:
* - function marked noinline
* - stack variables are marked volatile
* - stack variables are written (memset()) and read (pr_info())
* - function has external effects (pr_info())
* */
static int noinline recursive_loop(int remaining)
{
volatile char buf[REC_STACK_SIZE];
memset((void *)buf, remaining & 0xFF, sizeof(buf));
pr_info("loop %d/%d ...\n", (int)buf[remaining % sizeof(buf)],
recur_count);
if (!remaining)
return 0;
else
return recursive_loop(remaining - 1);
}
/* If the depth is negative, use the default, otherwise keep parameter. */
void __init lkdtm_bugs_init(int *recur_param)
{
if (*recur_param < 0)
*recur_param = recur_count;
else
recur_count = *recur_param;
}
void lkdtm_PANIC(void)
{
panic("dumptest");
}
void lkdtm_BUG(void)
{
BUG();
}
static int warn_counter;
void lkdtm_WARNING(void)
{
WARN(1, "Warning message trigger count: %d\n", warn_counter++);
}
void lkdtm_EXCEPTION(void)
{
*((volatile int *) 0) = 0;
}
void lkdtm_LOOP(void)
{
for (;;)
;
}
void lkdtm_EXHAUST_STACK(void)
{
pr_info("Calling function with %d frame size to depth %d ...\n",
REC_STACK_SIZE, recur_count);
recursive_loop(recur_count);
pr_info("FAIL: survived without exhausting stack?!\n");
}
static noinline void __lkdtm_CORRUPT_STACK(void *stack)
{
memset(stack, '\xff', 64);
}
/* This should trip the stack canary, not corrupt the return address. */
noinline void lkdtm_CORRUPT_STACK(void)
{
/* Use default char array length that triggers stack protection. */
char data[8] __aligned(sizeof(void *));
__lkdtm_CORRUPT_STACK(&data);
pr_info("Corrupted stack containing char array ...\n");
}
/* Same as above but will only get a canary with -fstack-protector-strong */
noinline void lkdtm_CORRUPT_STACK_STRONG(void)
{
union {
unsigned short shorts[4];
unsigned long *ptr;
} data __aligned(sizeof(void *));
__lkdtm_CORRUPT_STACK(&data);
pr_info("Corrupted stack containing union ...\n");
}
void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)
{
static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5};
u32 *p;
u32 val = 0x12345678;
p = (u32 *)(data + 1);
if (*p == 0)
val = 0x87654321;
*p = val;
}
void lkdtm_SOFTLOCKUP(void)
{
preempt_disable();
for (;;)
cpu_relax();
}
void lkdtm_HARDLOCKUP(void)
{
local_irq_disable();
for (;;)
cpu_relax();
}
void lkdtm_SPINLOCKUP(void)
{
/* Must be called twice to trigger. */
spin_lock(&lock_me_up);
/* Let sparse know we intended to exit holding the lock. */
__release(&lock_me_up);
}
void lkdtm_HUNG_TASK(void)
{
set_current_state(TASK_UNINTERRUPTIBLE);
schedule();
}
void lkdtm_CORRUPT_LIST_ADD(void)
{
/*
* Initially, an empty list via LIST_HEAD:
* test_head.next = &test_head
* test_head.prev = &test_head
*/
LIST_HEAD(test_head);
struct lkdtm_list good, bad;
void *target[2] = { };
void *redirection = &target;
pr_info("attempting good list addition\n");
/*
* Adding to the list performs these actions:
* test_head.next->prev = &good.node
* good.node.next = test_head.next
* good.node.prev = test_head
* test_head.next = good.node
*/
list_add(&good.node, &test_head);
pr_info("attempting corrupted list addition\n");
/*
* In simulating this "write what where" primitive, the "what" is
* the address of &bad.node, and the "where" is the address held
* by "redirection".
*/
test_head.next = redirection;
list_add(&bad.node, &test_head);
if (target[0] == NULL && target[1] == NULL)
pr_err("Overwrite did not happen, but no BUG?!\n");
else
pr_err("list_add() corruption not detected!\n");
}
void lkdtm_CORRUPT_LIST_DEL(void)
{
LIST_HEAD(test_head);
struct lkdtm_list item;
void *target[2] = { };
void *redirection = &target;
list_add(&item.node, &test_head);
pr_info("attempting good list removal\n");
list_del(&item.node);
pr_info("attempting corrupted list removal\n");
list_add(&item.node, &test_head);
/* As with the list_add() test above, this corrupts "next". */
item.node.next = redirection;
list_del(&item.node);
if (target[0] == NULL && target[1] == NULL)
pr_err("Overwrite did not happen, but no BUG?!\n");
else
pr_err("list_del() corruption not detected!\n");
}
/* Test if unbalanced set_fs(KERNEL_DS)/set_fs(USER_DS) check exists. */
void lkdtm_CORRUPT_USER_DS(void)
{
pr_info("setting bad task size limit\n");
set_fs(KERNEL_DS);
/* Make sure we do not keep running with a KERNEL_DS! */
force_sig(SIGKILL);
}
/* Test that VMAP_STACK is actually allocating with a leading guard page */
void lkdtm_STACK_GUARD_PAGE_LEADING(void)
{
const unsigned char *stack = task_stack_page(current);
const unsigned char *ptr = stack - 1;
volatile unsigned char byte;
pr_info("attempting bad read from page below current stack\n");
byte = *ptr;
pr_err("FAIL: accessed page before stack!\n");
}
/* Test that VMAP_STACK is actually allocating with a trailing guard page */
void lkdtm_STACK_GUARD_PAGE_TRAILING(void)
{
const unsigned char *stack = task_stack_page(current);
const unsigned char *ptr = stack + THREAD_SIZE;
volatile unsigned char byte;
pr_info("attempting bad read from page above current stack\n");
byte = *ptr;
pr_err("FAIL: accessed page after stack!\n");
}
void lkdtm_UNSET_SMEP(void)
{
#ifdef CONFIG_X86_64
#define MOV_CR4_DEPTH 64
void (*direct_write_cr4)(unsigned long val);
unsigned char *insn;
unsigned long cr4;
int i;
cr4 = native_read_cr4();
if ((cr4 & X86_CR4_SMEP) != X86_CR4_SMEP) {
pr_err("FAIL: SMEP not in use\n");
return;
}
cr4 &= ~(X86_CR4_SMEP);
pr_info("trying to clear SMEP normally\n");
native_write_cr4(cr4);
if (cr4 == native_read_cr4()) {
pr_err("FAIL: pinning SMEP failed!\n");
cr4 |= X86_CR4_SMEP;
pr_info("restoring SMEP\n");
native_write_cr4(cr4);
return;
}
pr_info("ok: SMEP did not get cleared\n");
/*
* To test the post-write pinning verification we need to call
* directly into the middle of native_write_cr4() where the
* cr4 write happens, skipping any pinning. This searches for
* the cr4 writing instruction.
*/
insn = (unsigned char *)native_write_cr4;
for (i = 0; i < MOV_CR4_DEPTH; i++) {
/* mov %rdi, %cr4 */
if (insn[i] == 0x0f && insn[i+1] == 0x22 && insn[i+2] == 0xe7)
break;
/* mov %rdi,%rax; mov %rax, %cr4 */
if (insn[i] == 0x48 && insn[i+1] == 0x89 &&
insn[i+2] == 0xf8 && insn[i+3] == 0x0f &&
insn[i+4] == 0x22 && insn[i+5] == 0xe0)
break;
}
if (i >= MOV_CR4_DEPTH) {
pr_info("ok: cannot locate cr4 writing call gadget\n");
return;
}
direct_write_cr4 = (void *)(insn + i);
pr_info("trying to clear SMEP with call gadget\n");
direct_write_cr4(cr4);
if (native_read_cr4() & X86_CR4_SMEP) {
pr_info("ok: SMEP removal was reverted\n");
} else {
pr_err("FAIL: cleared SMEP not detected!\n");
cr4 |= X86_CR4_SMEP;
pr_info("restoring SMEP\n");
native_write_cr4(cr4);
}
#else
pr_err("FAIL: this test is x86_64-only\n");
#endif
}