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kasan: separate double free case from invalid free 

Currently, KASAN describes all invalid-free/double-free bugs as
"double-free or invalid-free".  This is ambiguous.

KASAN should report "double-free" when a double-free is a more likely
cause (the address points to the start of an object) and report
"invalid-free" otherwise [1].

[1] https://bugzilla.kernel.org/show_bug.cgi?id=212193

Link: https://lkml.kernel.org/r/20220615062219.22618-1-Kuan-Ying.Lee@mediatek.com
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Yee Lee <yee.lee@mediatek.com>
Cc: Andrew Yang <andrew.yang@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kuan-Ying Lee 2022-06-15 14:22:18 +08:00 committed by akpm
parent cb55b83862
commit 3de0de7580
3 changed files with 14 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
mm/kasan/common.c
View File

@ -343,7 +343,7 @@ static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
if (unlikely(nearest_obj(cache, virt_to_slab(object), object) !=
object)) {
kasan_report_invalid_free(tagged_object, ip);
kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_INVALID_FREE);
return true;
}
@ -352,7 +352,7 @@ static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
return false;
if (!kasan_byte_accessible(tagged_object)) {
kasan_report_invalid_free(tagged_object, ip);
kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_DOUBLE_FREE);
return true;
}
@ -377,12 +377,12 @@ bool __kasan_slab_free(struct kmem_cache *cache, void *object,
static inline bool ____kasan_kfree_large(void *ptr, unsigned long ip)
{
if (ptr != page_address(virt_to_head_page(ptr))) {
kasan_report_invalid_free(ptr, ip);
kasan_report_invalid_free(ptr, ip, KASAN_REPORT_INVALID_FREE);
return true;
}
if (!kasan_byte_accessible(ptr)) {
kasan_report_invalid_free(ptr, ip);
kasan_report_invalid_free(ptr, ip, KASAN_REPORT_DOUBLE_FREE);
return true;
}

3
mm/kasan/kasan.h
View File

@ -125,6 +125,7 @@ static inline bool kasan_sync_fault_possible(void)
enum kasan_report_type {
KASAN_REPORT_ACCESS,
KASAN_REPORT_INVALID_FREE,
KASAN_REPORT_DOUBLE_FREE,
};
struct kasan_report_info {
@ -277,7 +278,7 @@ static inline void kasan_print_address_stack_frame(const void *addr) { }
bool kasan_report(unsigned long addr, size_t size,
bool is_write, unsigned long ip);
void kasan_report_invalid_free(void *object, unsigned long ip);
void kasan_report_invalid_free(void *object, unsigned long ip, enum kasan_report_type type);
struct page *kasan_addr_to_page(const void *addr);
struct slab *kasan_addr_to_slab(const void *addr);

12
mm/kasan/report.c
View File

@ -176,8 +176,12 @@ static void end_report(unsigned long *flags, void *addr)
static void print_error_description(struct kasan_report_info *info)
{
if (info->type == KASAN_REPORT_INVALID_FREE) {
pr_err("BUG: KASAN: double-free or invalid-free in %pS\n",
(void *)info->ip);
pr_err("BUG: KASAN: invalid-free in %pS\n", (void *)info->ip);
return;
}
if (info->type == KASAN_REPORT_DOUBLE_FREE) {
pr_err("BUG: KASAN: double-free in %pS\n", (void *)info->ip);
return;
}
@ -433,7 +437,7 @@ static void print_report(struct kasan_report_info *info)
}
}
void kasan_report_invalid_free(void *ptr, unsigned long ip)
void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_type type)
{
unsigned long flags;
struct kasan_report_info info;
@ -448,7 +452,7 @@ void kasan_report_invalid_free(void *ptr, unsigned long ip)
start_report(&flags, true);
info.type = KASAN_REPORT_INVALID_FREE;
info.type = type;
info.access_addr = ptr;
info.first_bad_addr = kasan_reset_tag(ptr);
info.access_size = 0;