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string: Add additional __realloc_size() annotations for "dup" helpers

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Several other "dup"-style interfaces could use the __realloc_size()
attribute. (As a reminder to myself and others: "realloc" is used here
instead of "alloc" because the "alloc_size" attribute implies that the
memory contents are uninitialized. Since we're copying contents into the
resulting allocation, it must use "realloc_size" to avoid confusing the
compiler's optimization passes.)

Add KUnit test coverage where possible. (KUnit still does not have the
ability to manipulate userspace memory.)

Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://lore.kernel.org/r/20240502145218.it.729-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2024-05-01 16:32:02 -07:00
parent 74df22453c
commit 7d78a77733
2 changed files with 34 additions and 5 deletions
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13
include/linux/string.h
View File

@ -14,8 +14,8 @@
#include <uapi/linux/string.h>
extern char *strndup_user(const char __user *, long);
extern void *memdup_user(const void __user *, size_t);
extern void *vmemdup_user(const void __user *, size_t);
extern void *memdup_user(const void __user *, size_t) __realloc_size(2);
extern void *vmemdup_user(const void __user *, size_t) __realloc_size(2);
extern void *memdup_user_nul(const void __user *, size_t);
/**
@ -27,7 +27,8 @@ extern void *memdup_user_nul(const void __user *, size_t);
* Return: an ERR_PTR() on failure. Result is physically
* contiguous, to be freed by kfree().
*/
static inline void *memdup_array_user(const void __user *src, size_t n, size_t size)
static inline __realloc_size(2, 3)
void *memdup_array_user(const void __user *src, size_t n, size_t size)
{
size_t nbytes;
@ -46,7 +47,8 @@ static inline void *memdup_array_user(const void __user *src, size_t n, size_t s
* Return: an ERR_PTR() on failure. Result may be not
* physically contiguous. Use kvfree() to free.
*/
static inline void *vmemdup_array_user(const void __user *src, size_t n, size_t size)
static inline __realloc_size(2, 3)
void *vmemdup_array_user(const void __user *src, size_t n, size_t size)
{
size_t nbytes;
@ -285,7 +287,8 @@ extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __realloc_size(2);
extern void *kvmemdup(const void *src, size_t len, gfp_t gfp) __realloc_size(2);
extern char *kmemdup_nul(const char *s, size_t len, gfp_t gfp);
extern void *kmemdup_array(const void *src, size_t element_size, size_t count, gfp_t gfp);
extern void *kmemdup_array(const void *src, size_t element_size, size_t count, gfp_t gfp)
__realloc_size(2, 3);
/* lib/argv_split.c */
extern char **argv_split(gfp_t gfp, const char *str, int *argcp);

26
lib/fortify_kunit.c
View File

@ -363,6 +363,31 @@ DEFINE_ALLOC_SIZE_TEST_PAIR(kvmalloc)
} while (0)
DEFINE_ALLOC_SIZE_TEST_PAIR(devm_kmalloc)
static const char * const test_strs[] = {
"",
"Hello there",
"A longer string, just for variety",
};
#define TEST_realloc(checker) do { \
gfp_t gfp = GFP_KERNEL; \
size_t len; \
int i; \
\
for (i = 0; i < ARRAY_SIZE(test_strs); i++) { \
len = strlen(test_strs[i]); \
KUNIT_EXPECT_EQ(test, __builtin_constant_p(len), 0); \
checker(len, kmemdup_array(test_strs[i], len, 1, gfp), \
kfree(p)); \
checker(len, kmemdup(test_strs[i], len, gfp), \
kfree(p)); \
} \
} while (0)
static void fortify_test_realloc_size(struct kunit *test)
{
TEST_realloc(check_dynamic);
}
/*
* We can't have an array at the end of a structure or else
* builds without -fstrict-flex-arrays=3 will report them as
@ -1046,6 +1071,7 @@ static struct kunit_case fortify_test_cases[] = {
KUNIT_CASE(fortify_test_alloc_size_kvmalloc_dynamic),
KUNIT_CASE(fortify_test_alloc_size_devm_kmalloc_const),
KUNIT_CASE(fortify_test_alloc_size_devm_kmalloc_dynamic),
KUNIT_CASE(fortify_test_realloc_size),
KUNIT_CASE(fortify_test_strlen),
KUNIT_CASE(fortify_test_strnlen),
KUNIT_CASE(fortify_test_strcpy),