On Mon, 4 Jul 2022 at 01:15, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Wed, 15 Jun 2022 14:22:18 +0800 Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx> wrote: > > > 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 > > > > ... > > Could we please have some review of this? Looks reasonable to me. Looking through git log it seems the only reason to combine them was laziness/didn't seem important enough. Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> I will update syzkaller parsing of bug messages to not produce duplicates for existing double-frees. Not sure if anything needs to be done for other kernel testing systems. > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > > index c40c0e7b3b5f..707c3a527fcb 100644 > > --- a/mm/kasan/common.c > > +++ b/mm/kasan/common.c > > @@ -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; > > } > > > > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > > index 610d60d6e5b8..01c03e45acd4 100644 > > --- a/mm/kasan/kasan.h > > +++ b/mm/kasan/kasan.h > > @@ -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); > > diff --git a/mm/kasan/report.c b/mm/kasan/report.c > > index b341a191651d..fe3f606b3a98 100644 > > --- a/mm/kasan/report.c > > +++ b/mm/kasan/report.c > > @@ -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; > > -- > > 2.18.0 > >
