diff options
author | Walter Wu <walter-zh.wu@mediatek.com> | 2020-04-02 07:09:37 +0300 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-02 19:35:30 +0300 |
commit | 8cceeff48f23eede76de995df08cf665182ec8fb (patch) | |
tree | 468c4d594ab0533d8b19991e8497bb3701e833c2 | |
parent | 4027149abde8d57da4c4c4f498b310c85a297bba (diff) | |
download | linux-8cceeff48f23eede76de995df08cf665182ec8fb.tar.xz |
kasan: detect negative size in memory operation function
Patch series "fix the missing underflow in memory operation function", v4.
The patchset helps to produce a KASAN report when size is negative in
memory operation functions. It is helpful for programmer to solve an
undefined behavior issue. Patch 1 based on Dmitry's review and
suggestion, patch 2 is a test in order to verify the patch 1.
[1]https://bugzilla.kernel.org/show_bug.cgi?id=199341
[2]https://lore.kernel.org/linux-arm-kernel/20190927034338.15813-1-walter-zh.wu@mediatek.com/
This patch (of 2):
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
[cai@lca.pw: fix -Wdeclaration-after-statement warn]
Link: http://lkml.kernel.org/r/1583509030-27939-1-git-send-email-cai@lca.pw
[peterz@infradead.org: fix objtool warning]
Link: http://lkml.kernel.org/r/20200305095436.GV2596@hirez.programming.kicks-ass.net
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com>
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Link: http://lkml.kernel.org/r/20191112065302.7015-1-walter-zh.wu@mediatek.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | include/linux/kasan.h | 2 | ||||
-rw-r--r-- | mm/kasan/common.c | 26 | ||||
-rw-r--r-- | mm/kasan/generic.c | 9 | ||||
-rw-r--r-- | mm/kasan/generic_report.c | 11 | ||||
-rw-r--r-- | mm/kasan/kasan.h | 2 | ||||
-rw-r--r-- | mm/kasan/report.c | 5 | ||||
-rw-r--r-- | mm/kasan/tags.c | 9 | ||||
-rw-r--r-- | mm/kasan/tags_report.c | 11 |
8 files changed, 54 insertions, 21 deletions
diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 5cde9e7c2664..31314ca7c635 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -190,7 +190,7 @@ 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 6aa51723b92b..e61b4a492218 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -105,7 +105,8 @@ 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); } @@ -114,8 +115,9 @@ 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); } @@ -124,8 +126,9 @@ 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); } @@ -634,12 +637,21 @@ void kasan_free_shadow(const struct vm_struct *vm) #endif 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(); - __kasan_report(addr, size, is_write, ip); + bool ret = false; + + if (likely(report_enabled())) { + __kasan_report(addr, size, is_write, ip); + ret = true; + } + user_access_restore(flags); + + return ret; } #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 2d97efd4954f..e200acb2d292 100644 --- a/mm/kasan/generic_report.c +++ b/mm/kasan/generic_report.c @@ -110,6 +110,17 @@ 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 3a083274628e..e8f37199d885 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -153,7 +153,7 @@ 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 5ef9f24f566b..cf5c17d5e361 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..bee43717d6f0 100644 --- a/mm/kasan/tags_report.c +++ b/mm/kasan/tags_report.c @@ -60,6 +60,17 @@ const char *get_bug_type(struct kasan_access_info *info) } #endif + /* + * 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"; + return "invalid-access"; } |