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stronger secure mode when defining MI_SECURE=4: checks for double free, corrupted free list, and invalid pointer frees. Performance is impacted but not too much -- more perf testing is needed

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This commit is contained in:
daan 2019-10-18 18:11:04 -07:00
parent fdfa6ed260
commit 2affdbbd2e
8 changed files with 121 additions and 20 deletions
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45
include/mimalloc-internal.h
View file

@ -20,6 +20,18 @@ terms of the MIT license. A copy of the license can be found in the file
#define mi_trace_message(...)
#endif
#if defined(_MSC_VER)
#define mi_decl_noinline __declspec(noinline)
#define mi_attr_noreturn
#elif defined(__GNUC__) || defined(__clang__)
#define mi_decl_noinline __attribute__((noinline))
#define mi_attr_noreturn __attribute__((noreturn))
#else
#define mi_decl_noinline
#define mi_attr_noreturn
#endif
// "options.c"
void _mi_fputs(mi_output_fun* out, const char* prefix, const char* message);
void _mi_fprintf(mi_output_fun* out, const char* fmt, ...);
@ -28,6 +40,7 @@ void _mi_warning_message(const char* fmt, ...);
void _mi_verbose_message(const char* fmt, ...);
void _mi_trace_message(const char* fmt, ...);
void _mi_options_init(void);
void _mi_fatal_error(const char* fmt, ...) mi_attr_noreturn;
// "init.c"
extern mi_stats_t _mi_stats_main;
@ -124,13 +137,6 @@ bool _mi_page_is_valid(mi_page_t* page);
#define __has_builtin(x) 0
#endif
#if defined(_MSC_VER)
#define mi_decl_noinline __declspec(noinline)
#elif defined(__GNUC__) || defined(__clang__)
#define mi_decl_noinline __attribute__((noinline))
#else
#define mi_decl_noinline
#endif
/* -----------------------------------------------------------
@ -365,8 +371,12 @@ static inline void mi_page_set_has_aligned(mi_page_t* page, bool has_aligned) {
// Encoding/Decoding the free list next pointers
// -------------------------------------------------------------------
static inline mi_block_t* mi_block_nextx( uintptr_t cookie, mi_block_t* block ) {
#if MI_SECURE
static inline bool mi_is_in_same_segment(const void* p, const void* q) {
return (_mi_ptr_segment(p) == _mi_ptr_segment(q));
}
static inline mi_block_t* mi_block_nextx( uintptr_t cookie, const mi_block_t* block ) {
#if MI_SECURE
return (mi_block_t*)(block->next ^ cookie);
#else
UNUSED(cookie);
@ -374,7 +384,7 @@ static inline mi_block_t* mi_block_nextx( uintptr_t cookie, mi_block_t* block )
#endif
}
static inline void mi_block_set_nextx(uintptr_t cookie, mi_block_t* block, mi_block_t* next) {
static inline void mi_block_set_nextx(uintptr_t cookie, mi_block_t* block, const mi_block_t* next) {
#if MI_SECURE
block->next = (mi_encoded_t)next ^ cookie;
#else
@ -383,16 +393,25 @@ static inline void mi_block_set_nextx(uintptr_t cookie, mi_block_t* block, mi_bl
#endif
}
static inline mi_block_t* mi_block_next(mi_page_t* page, mi_block_t* block) {
static inline mi_block_t* mi_block_next(const mi_page_t* page, const mi_block_t* block) {
#if MI_SECURE
return mi_block_nextx(page->cookie,block);
mi_block_t* next = mi_block_nextx(page->cookie,block);
#if MI_SECURE >= 4
// check if next is at least in our segment range
// TODO: it is better to check if it is actually inside our page but that is more expensive
// to calculate. Perhaps with a relative free list this becomes feasible?
if (next!=NULL && !mi_is_in_same_segment(block, next)) {
_mi_fatal_error("corrupted free list entry at %p: %zx\n", block, (uintptr_t)next);
}
#endif
return next;
#else
UNUSED(page);
return mi_block_nextx(0, block);
#endif
}
static inline void mi_block_set_next(mi_page_t* page, mi_block_t* block, mi_block_t* next) {
static inline void mi_block_set_next(const mi_page_t* page, mi_block_t* block, const mi_block_t* next) {
#if MI_SECURE
mi_block_set_nextx(page->cookie,block,next);
#else

7
include/mimalloc-types.h
View file

@ -22,8 +22,11 @@ terms of the MIT license. A copy of the license can be found in the file
// Define MI_STAT as 1 to maintain statistics; set it to 2 to have detailed statistics (but costs some performance).
// #define MI_STAT 1
// Define MI_SECURE as 1 to encode free lists
// #define MI_SECURE 1
// Define MI_SECURE to enable security mitigations
// #define MI_SECURE 1 // guard page around metadata
// #define MI_SECURE 2 // guard page around each mimalloc page
// #define MI_SECURE 3 // encode free lists
// #define MI_SECURE 4 // all security enabled (checks for double free, corrupted free list and invalid pointer free)
#if !defined(MI_SECURE)
#define MI_SECURE 0