On Tue, 2019-11-12 at 14:53 +0800, Walter Wu wrote: > KASAN missed detecting size is a negative number in memset(), memcpy(), > and memmove(), it will cause out-of-bounds bug. So needs to be detected > by KASAN. > > If size is a negative number, then it has a reason to be defined as > out-of-bounds bug type. > Casting negative numbers to size_t would indeed turn up as > a large size_t and its value will be larger than ULONG_MAX/2, > so that this can qualify as out-of-bounds. > > KASAN report is shown below: > > BUG: KASAN: out-of-bounds in kmalloc_memmove_invalid_size+0x70/0xa0 > Read of size 18446744073709551608 at addr ffffff8069660904 by task cat/72 > > CPU: 2 PID: 72 Comm: cat Not tainted 5.4.0-rc1-next-20191004ajb-00001-gdb8af2f372b2-dirty #1 > Hardware name: linux,dummy-virt (DT) > Call trace: > dump_backtrace+0x0/0x288 > show_stack+0x14/0x20 > dump_stack+0x10c/0x164 > print_address_description.isra.9+0x68/0x378 > __kasan_report+0x164/0x1a0 > kasan_report+0xc/0x18 > check_memory_region+0x174/0x1d0 > memmove+0x34/0x88 > kmalloc_memmove_invalid_size+0x70/0xa0 > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=199341 > > Signed-off-by: Walter Wu <walter-zh.wu@xxxxxxxxxxxx> > Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Suggested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> > Cc: Alexander Potapenko <glider@xxxxxxxxxx> > Reported-by: kernel test robot <lkp@xxxxxxxxx> > --- > include/linux/kasan.h | 2 +- > mm/kasan/common.c | 25 ++++++++++++++++++------- > mm/kasan/generic.c | 9 +++++---- > mm/kasan/generic_report.c | 11 +++++++++++ > mm/kasan/kasan.h | 2 +- > mm/kasan/report.c | 5 +---- > mm/kasan/tags.c | 9 +++++---- > mm/kasan/tags_report.c | 11 +++++++++++ > 8 files changed, 53 insertions(+), 21 deletions(-) > > diff --git a/include/linux/kasan.h b/include/linux/kasan.h > index cc8a03cc9674..2ef6b8fc63ef 100644 > --- a/include/linux/kasan.h > +++ b/include/linux/kasan.h > @@ -180,7 +180,7 @@ void kasan_init_tags(void); > > void *kasan_reset_tag(const void *addr); > > -void kasan_report(unsigned long addr, size_t size, > +bool kasan_report(unsigned long addr, size_t size, > bool is_write, unsigned long ip); > > #else /* CONFIG_KASAN_SW_TAGS */ > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 6814d6d6a023..4bfce0af881f 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -102,7 +102,8 @@ EXPORT_SYMBOL(__kasan_check_write); > #undef memset > void *memset(void *addr, int c, size_t len) > { > - check_memory_region((unsigned long)addr, len, true, _RET_IP_); > + if (!check_memory_region((unsigned long)addr, len, true, _RET_IP_)) > + return NULL; > > return __memset(addr, c, len); > } > @@ -110,8 +111,9 @@ void *memset(void *addr, int c, size_t len) > #undef memmove > void *memmove(void *dest, const void *src, size_t len) > { > - check_memory_region((unsigned long)src, len, false, _RET_IP_); > - check_memory_region((unsigned long)dest, len, true, _RET_IP_); > + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || > + !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) > + return NULL; > > return __memmove(dest, src, len); > } > @@ -119,8 +121,9 @@ void *memmove(void *dest, const void *src, size_t len) > #undef memcpy > void *memcpy(void *dest, const void *src, size_t len) > { > - check_memory_region((unsigned long)src, len, false, _RET_IP_); > - check_memory_region((unsigned long)dest, len, true, _RET_IP_); > + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || > + !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) > + return NULL; > > return __memcpy(dest, src, len); > } > @@ -627,12 +630,20 @@ void kasan_free_shadow(const struct vm_struct *vm) > } > > extern void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip); > +extern bool report_enabled(void); > > -void kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) > +bool kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) > { > - unsigned long flags = user_access_save(); > + unsigned long flags; > + > + if (likely(!report_enabled())) > + return false; > + > + flags = user_access_save(); > __kasan_report(addr, size, is_write, ip); > user_access_restore(flags); > + > + return true; > } > > #ifdef CONFIG_MEMORY_HOTPLUG > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c > index 616f9dd82d12..56ff8885fe2e 100644 > --- a/mm/kasan/generic.c > +++ b/mm/kasan/generic.c > @@ -173,17 +173,18 @@ static __always_inline bool check_memory_region_inline(unsigned long addr, > if (unlikely(size == 0)) > return true; > > + if (unlikely(addr + size < addr)) > + return !kasan_report(addr, size, write, ret_ip); > + > if (unlikely((void *)addr < > kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { > - kasan_report(addr, size, write, ret_ip); > - return false; > + return !kasan_report(addr, size, write, ret_ip); > } > > if (likely(!memory_is_poisoned(addr, size))) > return true; > > - kasan_report(addr, size, write, ret_ip); > - return false; > + return !kasan_report(addr, size, write, ret_ip); > } > > bool check_memory_region(unsigned long addr, size_t size, bool write, > diff --git a/mm/kasan/generic_report.c b/mm/kasan/generic_report.c > index 36c645939bc9..c82bc3f52c9a 100644 > --- a/mm/kasan/generic_report.c > +++ b/mm/kasan/generic_report.c > @@ -107,6 +107,17 @@ static const char *get_wild_bug_type(struct kasan_access_info *info) > > const char *get_bug_type(struct kasan_access_info *info) > { > + /* > + * If access_size is a negative number, then it has reason to be > + * defined as out-of-bounds bug type. > + * > + * Casting negative numbers to size_t would indeed turn up as > + * a large size_t and its value will be larger than ULONG_MAX/2, > + * so that this can qualify as out-of-bounds. > + */ > + if (info->access_addr + info->access_size < info->access_addr) > + return "out-of-bounds"; > + > if (addr_has_shadow(info->access_addr)) > return get_shadow_bug_type(info); > return get_wild_bug_type(info); > diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h > index 35cff6bbb716..afada2ce14bf 100644 > --- a/mm/kasan/kasan.h > +++ b/mm/kasan/kasan.h > @@ -152,7 +152,7 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, > void *find_first_bad_addr(void *addr, size_t size); > const char *get_bug_type(struct kasan_access_info *info); > > -void kasan_report(unsigned long addr, size_t size, > +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); > > diff --git a/mm/kasan/report.c b/mm/kasan/report.c > index 621782100eaa..c94f8e9c78d4 100644 > --- a/mm/kasan/report.c > +++ b/mm/kasan/report.c > @@ -446,7 +446,7 @@ static void print_shadow_for_address(const void *addr) > } > } > > -static bool report_enabled(void) > +bool report_enabled(void) > { > if (current->kasan_depth) > return false; > @@ -478,9 +478,6 @@ void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned lon > void *untagged_addr; > unsigned long flags; > > - if (likely(!report_enabled())) > - return; > - > disable_trace_on_warning(); > > tagged_addr = (void *)addr; > diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c > index 0e987c9ca052..25b7734e7013 100644 > --- a/mm/kasan/tags.c > +++ b/mm/kasan/tags.c > @@ -86,6 +86,9 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, > if (unlikely(size == 0)) > return true; > > + if (unlikely(addr + size < addr)) > + return !kasan_report(addr, size, write, ret_ip); > + > tag = get_tag((const void *)addr); > > /* > @@ -111,15 +114,13 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, > untagged_addr = reset_tag((const void *)addr); > if (unlikely(untagged_addr < > kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { > - kasan_report(addr, size, write, ret_ip); > - return false; > + return !kasan_report(addr, size, write, ret_ip); > } > shadow_first = kasan_mem_to_shadow(untagged_addr); > shadow_last = kasan_mem_to_shadow(untagged_addr + size - 1); > for (shadow = shadow_first; shadow <= shadow_last; shadow++) { > if (*shadow != tag) { > - kasan_report(addr, size, write, ret_ip); > - return false; > + return !kasan_report(addr, size, write, ret_ip); > } > } > > diff --git a/mm/kasan/tags_report.c b/mm/kasan/tags_report.c > index 969ae08f59d7..1d412760551a 100644 > --- a/mm/kasan/tags_report.c > +++ b/mm/kasan/tags_report.c > @@ -36,6 +36,17 @@ > > const char *get_bug_type(struct kasan_access_info *info) > { > + /* > + * If access_size is a negative number, then it has reason to be > + * defined as out-of-bounds bug type. > + * > + * Casting negative numbers to size_t would indeed turn up as > + * a large size_t and its value will be larger than ULONG_MAX/2, > + * so that this can qualify as out-of-bounds. > + */ > + if (info->access_addr + info->access_size < info->access_addr) > + return "out-of-bounds"; > + > #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY > struct kasan_alloc_meta *alloc_meta; > struct kmem_cache *cache; Hi Andrey, Would you have any concerns? Thanks. Walter
