mirror of
https://github.com/torvalds/linux.git
synced 2024-11-29 23:51:37 +00:00
febebaf366
This new test ensures that fortified strscpy has the same behavior than vanilla strscpy (e.g. returning -E2BIG when src content is truncated). Finally, it generates a crash at runtime because there is a write overflow in destination string. Link: https://lkml.kernel.org/r/20201122162451.27551-5-laniel_francis@privacyrequired.com Signed-off-by: Francis Laniel <laniel_francis@privacyrequired.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Daniel Axtens <dja@axtens.net> Cc: Daniel Micay <danielmicay@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
83 lines
2.2 KiB
C
83 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Copyright (c) 2020 Francis Laniel <laniel_francis@privacyrequired.com>
|
|
*
|
|
* Add tests related to fortified functions in this file.
|
|
*/
|
|
#include "lkdtm.h"
|
|
#include <linux/string.h>
|
|
#include <linux/slab.h>
|
|
|
|
|
|
/*
|
|
* Calls fortified strscpy to test that it returns the same result as vanilla
|
|
* strscpy and generate a panic because there is a write overflow (i.e. src
|
|
* length is greater than dst length).
|
|
*/
|
|
void lkdtm_FORTIFIED_STRSCPY(void)
|
|
{
|
|
char *src;
|
|
char dst[5];
|
|
|
|
struct {
|
|
union {
|
|
char big[10];
|
|
char src[5];
|
|
};
|
|
} weird = { .big = "hello!" };
|
|
char weird_dst[sizeof(weird.src) + 1];
|
|
|
|
src = kstrdup("foobar", GFP_KERNEL);
|
|
|
|
if (src == NULL)
|
|
return;
|
|
|
|
/* Vanilla strscpy returns -E2BIG if size is 0. */
|
|
if (strscpy(dst, src, 0) != -E2BIG)
|
|
pr_warn("FAIL: strscpy() of 0 length did not return -E2BIG\n");
|
|
|
|
/* Vanilla strscpy returns -E2BIG if src is truncated. */
|
|
if (strscpy(dst, src, sizeof(dst)) != -E2BIG)
|
|
pr_warn("FAIL: strscpy() did not return -E2BIG while src is truncated\n");
|
|
|
|
/* After above call, dst must contain "foob" because src was truncated. */
|
|
if (strncmp(dst, "foob", sizeof(dst)) != 0)
|
|
pr_warn("FAIL: after strscpy() dst does not contain \"foob\" but \"%s\"\n",
|
|
dst);
|
|
|
|
/* Shrink src so the strscpy() below succeeds. */
|
|
src[3] = '\0';
|
|
|
|
/*
|
|
* Vanilla strscpy returns number of character copied if everything goes
|
|
* well.
|
|
*/
|
|
if (strscpy(dst, src, sizeof(dst)) != 3)
|
|
pr_warn("FAIL: strscpy() did not return 3 while src was copied entirely truncated\n");
|
|
|
|
/* After above call, dst must contain "foo" because src was copied. */
|
|
if (strncmp(dst, "foo", sizeof(dst)) != 0)
|
|
pr_warn("FAIL: after strscpy() dst does not contain \"foo\" but \"%s\"\n",
|
|
dst);
|
|
|
|
/* Test when src is embedded inside a union. */
|
|
strscpy(weird_dst, weird.src, sizeof(weird_dst));
|
|
|
|
if (strcmp(weird_dst, "hello") != 0)
|
|
pr_warn("FAIL: after strscpy() weird_dst does not contain \"hello\" but \"%s\"\n",
|
|
weird_dst);
|
|
|
|
/* Restore src to its initial value. */
|
|
src[3] = 'b';
|
|
|
|
/*
|
|
* Use strlen here so size cannot be known at compile time and there is
|
|
* a runtime write overflow.
|
|
*/
|
|
strscpy(dst, src, strlen(src));
|
|
|
|
pr_warn("FAIL: No overflow in above strscpy()\n");
|
|
|
|
kfree(src);
|
|
}
|