From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF052C4CED1 for ; Fri, 4 Oct 2019 08:02:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A30F82084D for ; Fri, 4 Oct 2019 08:02:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A30F82084D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4ACD86B0007; Fri, 4 Oct 2019 04:02:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 460356B0008; Fri, 4 Oct 2019 04:02:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3757A8E0003; Fri, 4 Oct 2019 04:02:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0237.hostedemail.com [216.40.44.237]) by kanga.kvack.org (Postfix) with ESMTP id 109AB6B0007 for ; Fri, 4 Oct 2019 04:02:22 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id A80478147 for ; Fri, 4 Oct 2019 08:02:21 +0000 (UTC) X-FDA: 76005359682.28.fan93_147821885b95a X-HE-Tag: fan93_147821885b95a X-Filterd-Recvd-Size: 10306 Received: from mailgw01.mediatek.com (unknown [210.61.82.183]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Fri, 4 Oct 2019 08:02:20 +0000 (UTC) X-UUID: 36bb4cb07a604004879dbefb87b1ff68-20191004 X-UUID: 36bb4cb07a604004879dbefb87b1ff68-20191004 Received: from mtkexhb02.mediatek.inc [(172.21.101.103)] by mailgw01.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.10 Build 0809 with TLS) with ESMTP id 585257250; Fri, 04 Oct 2019 16:02:12 +0800 Received: from mtkcas07.mediatek.inc (172.21.101.84) by mtkmbs07n1.mediatek.inc (172.21.101.16) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Fri, 4 Oct 2019 16:02:10 +0800 Received: from [172.21.84.99] (172.21.84.99) by mtkcas07.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Fri, 4 Oct 2019 16:02:10 +0800 Message-ID: <1570176131.19702.105.camel@mtksdccf07> Subject: Re: [PATCH] kasan: fix the missing underflow in memmove and memcpy with CONFIG_KASAN_GENERIC=y From: Walter Wu To: Dmitry Vyukov CC: Andrey Ryabinin , Alexander Potapenko , Matthias Brugger , LKML , kasan-dev , Linux-MM , Linux ARM , , wsd_upstream Date: Fri, 4 Oct 2019 16:02:11 +0800 In-Reply-To: <1570164140.19702.97.camel@mtksdccf07> References: <20190927034338.15813-1-walter-zh.wu@mediatek.com> <1569594142.9045.24.camel@mtksdccf07> <1569818173.17361.19.camel@mtksdccf07> <1570018513.19702.36.camel@mtksdccf07> <1570069078.19702.57.camel@mtksdccf07> <1570095525.19702.59.camel@mtksdccf07> <1570110681.19702.64.camel@mtksdccf07> <1570164140.19702.97.camel@mtksdccf07> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 2019-10-04 at 12:42 +0800, Walter Wu wrote: > On Thu, 2019-10-03 at 16:53 +0200, Dmitry Vyukov wrote: > > On Thu, Oct 3, 2019 at 3:51 PM Walter Wu wrote:> > > > > > > static void print_error_description(struct kasan_access_info *info) > > > { > > > - pr_err("BUG: KASAN: %s in %pS\n", > > > - get_bug_type(info), (void *)info->ip); > > > - pr_err("%s of size %zu at addr %px by task %s/%d\n", > > > - info->is_write ? "Write" : "Read", info->access_size, > > > - info->access_addr, current->comm, task_pid_nr(current)); > > > + if ((long)info->access_size < 0) { > > > + pr_err("BUG: KASAN: invalid size %zu in %pS\n", > > > + info->access_size, (void *)info->ip); > > > > I would not introduce a new bug type. > > These are parsed and used by some systems, e.g. syzbot. If size is > > user-controllable, then a new bug type for this will mean 2 bug > > reports. > > It also won't harm to print Read/Write, definitely the address, so no > > reason to special case this out of a dozen of report formats. > > This can qualify as out-of-bounds (definitely will cross some > > bounds!), so I would change get_bug_type() to return > > "slab-out-of-bounds" (as the most common OOB) in such case (with a > > comment). > > > Print Read/Write and address information, it is ok. > But if we can directly point to the root cause of this problem, why we > not do it? see 1) and 2) to get a point, if we print OOB, then user > needs one minute to think what is root case of this problem, but if we > print invalid size, then user can directly get root case. this is my > original thinking. > 1)Invalid size is true then OOB is true. > 2)OOB is true then invalid size may be true or false. > > But I see you say some systems have used bug report so that avoid this > trouble, i will print the wrong type is "out-of-bound" in a unified way > when size<0. > Updated my patch, please help to review it. thanks. commit 13e10a7e4264eb25c5a14193068027afc9c261f6 Author: Walter-zh Wu Date: Fri Oct 4 15:27:17 2019 +0800 kasan: detect negative size in memory operation function It is an undefined behavior to pass a negative value to memset()/memcpy()/memmove() , so need to be detected by KASAN. If size is negative value, then it will be larger than ULONG_MAX/2, so that we will qualify as out-of-bounds issue. KASAN report: 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 Reported -by: Dmitry Vyukov Suggested-by: Dmitry Vyukov diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 49cc4d570a40..06942cf585cc 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -283,6 +283,23 @@ static noinline void __init kmalloc_oob_in_memset(void) kfree(ptr); } +static noinline void __init kmalloc_memmove_invalid_size(void) +{ + char *ptr; + size_t size = 64; + + pr_info("invalid size in memmove\n"); + ptr = kmalloc(size, GFP_KERNEL); + if (!ptr) { + pr_err("Allocation failed\n"); + return; + } + + memset((char *)ptr, 0, 64); + memmove((char *)ptr, (char *)ptr + 4, -2); + kfree(ptr); +} + static noinline void __init kmalloc_uaf(void) { char *ptr; @@ -773,6 +790,7 @@ static int __init kmalloc_tests_init(void) kmalloc_oob_memset_4(); kmalloc_oob_memset_8(); kmalloc_oob_memset_16(); + kmalloc_memmove_invalid_size(); kmalloc_uaf(); kmalloc_uaf_memset(); kmalloc_uaf2(); diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 6814d6d6a023..97dd6eecc3e7 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); } @@ -110,7 +111,8 @@ 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_); + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_)) + return NULL; check_memory_region((unsigned long)dest, len, true, _RET_IP_); return __memmove(dest, src, len); @@ -119,7 +121,8 @@ 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_); + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_)) + return NULL; check_memory_region((unsigned long)dest, len, true, _RET_IP_); return __memcpy(dest, src, len); diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index 616f9dd82d12..02148a317d27 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -173,6 +173,11 @@ static __always_inline bool check_memory_region_inline(unsigned long addr, if (unlikely(size == 0)) return true; + if (unlikely((long)size < 0)) { + kasan_report(addr, size, write, ret_ip); + return false; + } + if (unlikely((void *)addr < kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { kasan_report(addr, size, write, ret_ip); diff --git a/mm/kasan/generic_report.c b/mm/kasan/generic_report.c index 36c645939bc9..ae9596210394 100644 --- a/mm/kasan/generic_report.c +++ b/mm/kasan/generic_report.c @@ -107,6 +107,13 @@ 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 < 0, then it will be larger than ULONG_MAX/2, + * so that this can qualify as out-of-bounds. + */ + if ((long)info->access_size < 0) + 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/tags.c b/mm/kasan/tags.c index 0e987c9ca052..b829535a3ad7 100644 --- a/mm/kasan/tags.c +++ b/mm/kasan/tags.c @@ -86,6 +86,11 @@ bool check_memory_region(unsigned long addr, size_t size, bool write, if (unlikely(size == 0)) return true; + if (unlikely((long)size < 0)) { + kasan_report(addr, size, write, ret_ip); + return false; + } + tag = get_tag((const void *)addr); /* diff --git a/mm/kasan/tags_report.c b/mm/kasan/tags_report.c index 969ae08f59d7..1e1ca81214b5 100644 --- a/mm/kasan/tags_report.c +++ b/mm/kasan/tags_report.c @@ -36,6 +36,13 @@ const char *get_bug_type(struct kasan_access_info *info) { + /* + * if access_size < 0, then it will be larger than ULONG_MAX/2, + * so that this can qualify as out-of-bounds. + */ + if ((long)info->access_size < 0) + return "out-of-bounds"; + #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY struct kasan_alloc_meta *alloc_meta; struct kmem_cache *cache;