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test_printf: test printf family at runtime

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This adds a simple module for testing the kernel's printf facilities.
Previously, some %p extensions have caused a wrong return value in case
the entire output didn't fit and/or been unusable in kasprintf().  This
should help catch such issues.  Also, it should help ensure that changes
to the formatting algorithms don't break anything.

I'm not sure if we have a struct dentry or struct file lying around at
boot time or if we can fake one, but most %p extensions should be
testable, as should the ordinary number and string formatting.

The nature of vararg functions means we can't use a more conventional
table-driven approach.

For now, this is mostly a skeleton; contributions are very
welcome. Some tests are/will be slightly annoying to write, since the
expected output depends on stuff like CONFIG_*, sizeof(long), runtime
values etc.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Martin Kletzander <mkletzan@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rasmus Villemoes 2015-11-06 16:30:29 -08:00 committed by Linus Torvalds
parent 80c9eb46fa
commit 707cc7280f
3 changed files with 366 additions and 0 deletions
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3
lib/Kconfig.debug
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@ -1686,6 +1686,9 @@ config TEST_STRING_HELPERS
config TEST_KSTRTOX
tristate "Test kstrto*() family of functions at runtime"
config TEST_PRINTF
tristate "Test printf() family of functions at runtime"
config TEST_RHASHTABLE
tristate "Perform selftest on resizable hash table"
default n

1
lib/Makefile
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@ -42,6 +42,7 @@ obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
obj-$(CONFIG_TEST_PRINTF) += test_printf.o
ifeq ($(CONFIG_DEBUG_KOBJECT),y)
CFLAGS_kobject.o += -DDEBUG

362
lib/test_printf.c Normal file
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@ -0,0 +1,362 @@
/*
* Test cases for printf facility.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/socket.h>
#include <linux/in.h>
#define BUF_SIZE 256
#define FILL_CHAR '$'
#define PTR1 ((void*)0x01234567)
#define PTR2 ((void*)(long)(int)0xfedcba98)
#if BITS_PER_LONG == 64
#define PTR1_ZEROES "000000000"
#define PTR1_SPACES " "
#define PTR1_STR "1234567"
#define PTR2_STR "fffffffffedcba98"
#define PTR_WIDTH 16
#else
#define PTR1_ZEROES "0"
#define PTR1_SPACES " "
#define PTR1_STR "1234567"
#define PTR2_STR "fedcba98"
#define PTR_WIDTH 8
#endif
#define PTR_WIDTH_STR stringify(PTR_WIDTH)
static unsigned total_tests __initdata;
static unsigned failed_tests __initdata;
static char *test_buffer __initdata;
static int __printf(4, 0) __init
do_test(int bufsize, const char *expect, int elen,
const char *fmt, va_list ap)
{
va_list aq;
int ret, written;
total_tests++;
memset(test_buffer, FILL_CHAR, BUF_SIZE);
va_copy(aq, ap);
ret = vsnprintf(test_buffer, bufsize, fmt, aq);
va_end(aq);
if (ret != elen) {
pr_warn("vsnprintf(buf, %d, \"%s\", ...) returned %d, expected %d\n",
bufsize, fmt, ret, elen);
return 1;
}
if (!bufsize) {
if (memchr_inv(test_buffer, FILL_CHAR, BUF_SIZE)) {
pr_warn("vsnprintf(buf, 0, \"%s\", ...) wrote to buffer\n",
fmt);
return 1;
}
return 0;
}
written = min(bufsize-1, elen);
if (test_buffer[written]) {
pr_warn("vsnprintf(buf, %d, \"%s\", ...) did not nul-terminate buffer\n",
bufsize, fmt);
return 1;
}
if (memcmp(test_buffer, expect, written)) {
pr_warn("vsnprintf(buf, %d, \"%s\", ...) wrote '%s', expected '%.*s'\n",
bufsize, fmt, test_buffer, written, expect);
return 1;
}
return 0;
}
static void __printf(3, 4) __init
__test(const char *expect, int elen, const char *fmt, ...)
{
va_list ap;
int rand;
char *p;
BUG_ON(elen >= BUF_SIZE);
va_start(ap, fmt);
/*
* Every fmt+args is subjected to four tests: Three where we
* tell vsnprintf varying buffer sizes (plenty, not quite
* enough and 0), and then we also test that kvasprintf would
* be able to print it as expected.
*/
failed_tests += do_test(BUF_SIZE, expect, elen, fmt, ap);
rand = 1 + prandom_u32_max(elen+1);
/* Since elen < BUF_SIZE, we have 1 <= rand <= BUF_SIZE. */
failed_tests += do_test(rand, expect, elen, fmt, ap);
failed_tests += do_test(0, expect, elen, fmt, ap);
p = kvasprintf(GFP_KERNEL, fmt, ap);
if (p) {
if (memcmp(p, expect, elen+1)) {
pr_warn("kvasprintf(..., \"%s\", ...) returned '%s', expected '%s'\n",
fmt, p, expect);
failed_tests++;
}
kfree(p);
}
va_end(ap);
}
#define test(expect, fmt, ...) \
__test(expect, strlen(expect), fmt, ##__VA_ARGS__)
static void __init
test_basic(void)
{
/* Work around annoying "warning: zero-length gnu_printf format string". */
char nul = '\0';
test("", &nul);
test("100%", "100%%");
test("xxx%yyy", "xxx%cyyy", '%');
__test("xxx\0yyy", 7, "xxx%cyyy", '\0');
}
static void __init
test_number(void)
{
test("0x1234abcd ", "%#-12x", 0x1234abcd);
test(" 0x1234abcd", "%#12x", 0x1234abcd);
test("0|001| 12|+123| 1234|-123|-1234", "%d|%03d|%3d|%+d|% d|%+d|% d", 0, 1, 12, 123, 1234, -123, -1234);
}
static void __init
test_string(void)
{
test("", "%s%.0s", "", "123");
test("ABCD|abc|123", "%s|%.3s|%.*s", "ABCD", "abcdef", 3, "123456");
test("1 | 2|3 | 4|5 ", "%-3s|%3s|%-*s|%*s|%*s", "1", "2", 3, "3", 3, "4", -3, "5");
/*
* POSIX and C99 say that a missing precision should be
* treated as a precision of 0. However, the kernel's printf
* implementation treats this case as if the . wasn't
* present. Let's add a test case documenting the current
* behaviour; should anyone ever feel the need to follow the
* standards more closely, this can be revisited.
*/
test("a||", "%.s|%.0s|%.*s", "a", "b", 0, "c");
test("a | | ", "%-3.s|%-3.0s|%-3.*s", "a", "b", 0, "c");
}
static void __init
plain(void)
{
test(PTR1_ZEROES PTR1_STR " " PTR2_STR, "%p %p", PTR1, PTR2);
/*
* The field width is overloaded for some %p extensions to
* pass another piece of information. For plain pointers, the
* behaviour is slightly odd: One cannot pass either the 0
* flag nor a precision to %p without gcc complaining, and if
* one explicitly gives a field width, the number is no longer
* zero-padded.
*/
test("|" PTR1_STR PTR1_SPACES " | " PTR1_SPACES PTR1_STR "|",
"|%-*p|%*p|", PTR_WIDTH+2, PTR1, PTR_WIDTH+2, PTR1);
test("|" PTR2_STR " | " PTR2_STR "|",
"|%-*p|%*p|", PTR_WIDTH+2, PTR2, PTR_WIDTH+2, PTR2);
/*
* Unrecognized %p extensions are treated as plain %p, but the
* alphanumeric suffix is ignored (that is, does not occur in
* the output.)
*/
test("|"PTR1_ZEROES PTR1_STR"|", "|%p0y|", PTR1);
test("|"PTR2_STR"|", "|%p0y|", PTR2);
}
static void __init
symbol_ptr(void)
{
}
static void __init
kernel_ptr(void)
{
}
static void __init
struct_resource(void)
{
}
static void __init
addr(void)
{
}
static void __init
escaped_str(void)
{
}
static void __init
hex_string(void)
{
const char buf[3] = {0xc0, 0xff, 0xee};
test("c0 ff ee|c0:ff:ee|c0-ff-ee|c0ffee",
"%3ph|%3phC|%3phD|%3phN", buf, buf, buf, buf);
test("c0 ff ee|c0:ff:ee|c0-ff-ee|c0ffee",
"%*ph|%*phC|%*phD|%*phN", 3, buf, 3, buf, 3, buf, 3, buf);
}
static void __init
mac(void)
{
const u8 addr[6] = {0x2d, 0x48, 0xd6, 0xfc, 0x7a, 0x05};
test("2d:48:d6:fc:7a:05", "%pM", addr);
test("05:7a:fc:d6:48:2d", "%pMR", addr);
test("2d-48-d6-fc-7a-05", "%pMF", addr);
test("2d48d6fc7a05", "%pm", addr);
test("057afcd6482d", "%pmR", addr);
}
static void __init
ip4(void)
{
struct sockaddr_in sa;
sa.sin_family = AF_INET;
sa.sin_port = cpu_to_be16(12345);
sa.sin_addr.s_addr = cpu_to_be32(0x7f000001);
test("127.000.000.001|127.0.0.1", "%pi4|%pI4", &sa.sin_addr, &sa.sin_addr);
test("127.000.000.001|127.0.0.1", "%piS|%pIS", &sa, &sa);
sa.sin_addr.s_addr = cpu_to_be32(0x01020304);
test("001.002.003.004:12345|1.2.3.4:12345", "%piSp|%pISp", &sa, &sa);
}
static void __init
ip6(void)
{
}
static void __init
ip(void)
{
ip4();
ip6();
}
static void __init
uuid(void)
{
const char uuid[16] = {0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7,
0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf};
test("00010203-0405-0607-0809-0a0b0c0d0e0f", "%pUb", uuid);
test("00010203-0405-0607-0809-0A0B0C0D0E0F", "%pUB", uuid);
test("03020100-0504-0706-0809-0a0b0c0d0e0f", "%pUl", uuid);
test("03020100-0504-0706-0809-0A0B0C0D0E0F", "%pUL", uuid);
}
static void __init
dentry(void)
{
}
static void __init
struct_va_format(void)
{
}
static void __init
struct_clk(void)
{
}
static void __init
bitmap(void)
{
DECLARE_BITMAP(bits, 20);
const int primes[] = {2,3,5,7,11,13,17,19};
int i;
bitmap_zero(bits, 20);
test("00000|00000", "%20pb|%*pb", bits, 20, bits);
test("|", "%20pbl|%*pbl", bits, 20, bits);
for (i = 0; i < ARRAY_SIZE(primes); ++i)
set_bit(primes[i], bits);
test("a28ac|a28ac", "%20pb|%*pb", bits, 20, bits);
test("2-3,5,7,11,13,17,19|2-3,5,7,11,13,17,19", "%20pbl|%*pbl", bits, 20, bits);
bitmap_fill(bits, 20);
test("fffff|fffff", "%20pb|%*pb", bits, 20, bits);
test("0-19|0-19", "%20pbl|%*pbl", bits, 20, bits);
}
static void __init
netdev_features(void)
{
}
static void __init
test_pointer(void)
{
plain();
symbol_ptr();
kernel_ptr();
struct_resource();
addr();
escaped_str();
hex_string();
mac();
ip();
uuid();
dentry();
struct_va_format();
struct_clk();
bitmap();
netdev_features();
}
static int __init
test_printf_init(void)
{
test_buffer = kmalloc(BUF_SIZE, GFP_KERNEL);
if (!test_buffer)
return -ENOMEM;
test_basic();
test_number();
test_string();
test_pointer();
kfree(test_buffer);
if (failed_tests == 0)
pr_info("all %u tests passed\n", total_tests);
else
pr_warn("failed %u out of %u tests\n", failed_tests, total_tests);
return failed_tests ? -EINVAL : 0;
}
module_init(test_printf_init);
MODULE_AUTHOR("Rasmus Villemoes <linux@rasmusvillemoes.dk>");
MODULE_LICENSE("GPL");