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=ham 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 94B8CC10F14 for ; Thu, 3 Oct 2019 13:51:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4216220865 for ; Thu, 3 Oct 2019 13:51:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4216220865 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 BAF1D6B0005; Thu, 3 Oct 2019 09:51:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B60866B0006; Thu, 3 Oct 2019 09:51:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A268B8E0003; Thu, 3 Oct 2019 09:51:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0254.hostedemail.com [216.40.44.254]) by kanga.kvack.org (Postfix) with ESMTP id 7A5B76B0005 for ; Thu, 3 Oct 2019 09:51:32 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 0F538180AD7C3 for ; Thu, 3 Oct 2019 13:51:32 +0000 (UTC) X-FDA: 76002610824.15.badge41_647022d80c552 X-HE-Tag: badge41_647022d80c552 X-Filterd-Recvd-Size: 19194 Received: from mailgw01.mediatek.com (unknown [210.61.82.183]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Thu, 3 Oct 2019 13:51:29 +0000 (UTC) X-UUID: 3d904f6d175441b6a8b24f17d6deb2bc-20191003 X-UUID: 3d904f6d175441b6a8b24f17d6deb2bc-20191003 Received: from mtkcas08.mediatek.inc [(172.21.101.126)] by mailgw01.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.10 Build 0809 with TLS) with ESMTP id 1733192920; Thu, 03 Oct 2019 21:51:23 +0800 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs07n1.mediatek.inc (172.21.101.16) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Thu, 3 Oct 2019 21:51:21 +0800 Received: from [172.21.84.99] (172.21.84.99) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Thu, 3 Oct 2019 21:51:20 +0800 Message-ID: <1570110681.19702.64.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: Thu, 3 Oct 2019 21:51:21 +0800 In-Reply-To: <1570095525.19702.59.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> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N Content-Transfer-Encoding: quoted-printable 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 Thu, 2019-10-03 at 17:38 +0800, Walter Wu wrote: > On Thu, 2019-10-03 at 08:26 +0200, Dmitry Vyukov wrote: > > On Thu, Oct 3, 2019 at 4:18 AM Walter Wu = wrote: > > > > > > On Wed, 2019-10-02 at 15:57 +0200, Dmitry Vyukov wrote: > > > > On Wed, Oct 2, 2019 at 2:15 PM Walter Wu wrote: > > > > > > > > > > On Mon, 2019-09-30 at 12:36 +0800, Walter Wu wrote: > > > > > > On Fri, 2019-09-27 at 21:41 +0200, Dmitry Vyukov wrote: > > > > > > > On Fri, Sep 27, 2019 at 4:22 PM Walter Wu wrote: > > > > > > > > > > > > > > > > On Fri, 2019-09-27 at 15:07 +0200, Dmitry Vyukov wrote: > > > > > > > > > On Fri, Sep 27, 2019 at 5:43 AM Walter Wu wrote: > > > > > > > > > > > > > > > > > > > > memmove() and memcpy() have missing underflow issues. > > > > > > > > > > When -7 <=3D size < 0, then KASAN will miss to catch = the underflow issue. > > > > > > > > > > It looks like shadow start address and shadow end add= ress is the same, > > > > > > > > > > so it does not actually check anything. > > > > > > > > > > > > > > > > > > > > The following test is indeed not caught by KASAN: > > > > > > > > > > > > > > > > > > > > char *p =3D kmalloc(64, GFP_KERNEL); > > > > > > > > > > memset((char *)p, 0, 64); > > > > > > > > > > memmove((char *)p, (char *)p + 4, -2); > > > > > > > > > > kfree((char*)p); > > > > > > > > > > > > > > > > > > > > It should be checked here: > > > > > > > > > > > > > > > > > > > > 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_); > > > > > > > > > > > > > > > > > > > > return __memmove(dest, src, len); > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > We fix the shadow end address which is calculated, th= en generic KASAN > > > > > > > > > > get the right shadow end address and detect this unde= rflow issue. > > > > > > > > > > > > > > > > > > > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=3D199= 341 > > > > > > > > > > > > > > > > > > > > Signed-off-by: Walter Wu > > > > > > > > > > Reported-by: Dmitry Vyukov > > > > > > > > > > --- > > > > > > > > > > lib/test_kasan.c | 36 ++++++++++++++++++++++++++++= ++++++++ > > > > > > > > > > mm/kasan/generic.c | 8 ++++++-- > > > > > > > > > > 2 files changed, 42 insertions(+), 2 deletions(-) > > > > > > > > > > > > > > > > > > > > diff --git a/lib/test_kasan.c b/lib/test_kasan.c > > > > > > > > > > index b63b367a94e8..8bd014852556 100644 > > > > > > > > > > --- a/lib/test_kasan.c > > > > > > > > > > +++ b/lib/test_kasan.c > > > > > > > > > > @@ -280,6 +280,40 @@ static noinline void __init kmal= loc_oob_in_memset(void) > > > > > > > > > > kfree(ptr); > > > > > > > > > > } > > > > > > > > > > > > > > > > > > > > +static noinline void __init kmalloc_oob_in_memmove_u= nderflow(void) > > > > > > > > > > +{ > > > > > > > > > > + char *ptr; > > > > > > > > > > + size_t size =3D 64; > > > > > > > > > > + > > > > > > > > > > + pr_info("underflow out-of-bounds in memmove\n= "); > > > > > > > > > > + ptr =3D 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_oob_in_memmove_o= verflow(void) > > > > > > > > > > +{ > > > > > > > > > > + char *ptr; > > > > > > > > > > + size_t size =3D 64; > > > > > > > > > > + > > > > > > > > > > + pr_info("overflow out-of-bounds in memmove\n"= ); > > > > > > > > > > + ptr =3D kmalloc(size, GFP_KERNEL); > > > > > > > > > > + if (!ptr) { > > > > > > > > > > + pr_err("Allocation failed\n"); > > > > > > > > > > + return; > > > > > > > > > > + } > > > > > > > > > > + > > > > > > > > > > + memset((char *)ptr, 0, 64); > > > > > > > > > > + memmove((char *)ptr + size, (char *)ptr, 2); > > > > > > > > > > + kfree(ptr); > > > > > > > > > > +} > > > > > > > > > > + > > > > > > > > > > static noinline void __init kmalloc_uaf(void) > > > > > > > > > > { > > > > > > > > > > char *ptr; > > > > > > > > > > @@ -734,6 +768,8 @@ static int __init kmalloc_tests_i= nit(void) > > > > > > > > > > kmalloc_oob_memset_4(); > > > > > > > > > > kmalloc_oob_memset_8(); > > > > > > > > > > kmalloc_oob_memset_16(); > > > > > > > > > > + kmalloc_oob_in_memmove_underflow(); > > > > > > > > > > + kmalloc_oob_in_memmove_overflow(); > > > > > > > > > > kmalloc_uaf(); > > > > > > > > > > kmalloc_uaf_memset(); > > > > > > > > > > kmalloc_uaf2(); > > > > > > > > > > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c > > > > > > > > > > index 616f9dd82d12..34ca23d59e67 100644 > > > > > > > > > > --- a/mm/kasan/generic.c > > > > > > > > > > +++ b/mm/kasan/generic.c > > > > > > > > > > @@ -131,9 +131,13 @@ static __always_inline bool memo= ry_is_poisoned_n(unsigned long addr, > > > > > > > > > > size_= t size) > > > > > > > > > > { > > > > > > > > > > unsigned long ret; > > > > > > > > > > + void *shadow_start =3D kasan_mem_to_shadow((v= oid *)addr); > > > > > > > > > > + void *shadow_end =3D kasan_mem_to_shadow((voi= d *)addr + size - 1) + 1; > > > > > > > > > > > > > > > > > > > > - ret =3D memory_is_nonzero(kasan_mem_to_shadow= ((void *)addr), > > > > > > > > > > - kasan_mem_to_shadow((void *)a= ddr + size - 1) + 1); > > > > > > > > > > + if ((long)size < 0) > > > > > > > > > > + shadow_end =3D kasan_mem_to_shadow((v= oid *)addr + size); > > > > > > > > > > > > > > > > > > Hi Walter, > > > > > > > > > > > > > > > > > > Thanks for working on this. > > > > > > > > > > > > > > > > > > If size<0, does it make sense to continue at all? We wi= ll still check > > > > > > > > > 1PB of shadow memory? What happens when we pass such hu= ge range to > > > > > > > > > memory_is_nonzero? > > > > > > > > > Perhaps it's better to produce an error and bail out im= mediately if size<0? > > > > > > > > > > > > > > > > I agree with what you said. when size<0, it is indeed an = unreasonable > > > > > > > > behavior, it should be blocked from continuing to do. > > > > > > > > > > > > > > > > > > > > > > > > > Also, what's the failure mode of the tests? Didn't they= badly corrupt > > > > > > > > > memory? We tried to keep tests such that they produce t= he KASAN > > > > > > > > > reports, but don't badly corrupt memory b/c/ we need to= run all of > > > > > > > > > them. > > > > > > > > > > > > > > > > Maybe we should first produce KASAN reports and then go t= o execute > > > > > > > > memmove() or do nothing? It looks like it=E2=80=99s doing= the following.or? > > > > > > > > > > > > > > > > void *memmove(void *dest, const void *src, size_t len) > > > > > > > > { > > > > > > > > + if (long(len) <=3D 0) > > > > > > > > > > > > > > /\/\/\/\/\/\ > > > > > > > > > > > > > > This check needs to be inside of check_memory_region, other= wise we > > > > > > > will have similar problems in all other places that use > > > > > > > check_memory_region. > > > > > > Thanks for your reminder. > > > > > > > > > > > > bool check_memory_region(unsigned long addr, size_t size, bo= ol write, > > > > > > unsigned long ret_ip) > > > > > > { > > > > > > + if (long(size) < 0) { > > > > > > + kasan_report_invalid_size(src, dest, len, _RE= T_IP_); > > > > > > + return false; > > > > > > + } > > > > > > + > > > > > > return check_memory_region_inline(addr, size, write, = ret_ip); > > > > > > } > > > > > > > > > > > > > But check_memory_region already returns a bool, so we could= check that > > > > > > > bool and return early. > > > > > > > > > > > > When size<0, we should only show one KASAN report, and should= we only > > > > > > limit to return when size<0 is true? If yse, then __memmove()= will do > > > > > > nothing. > > > > > > > > > > > > > > > > > > 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, fals= e, > > > > > > _RET_IP_) > > > > > > + && long(size) < 0) > > > > > > + return; > > > > > > + > > > > > > check_memory_region((unsigned long)dest, len, true, _= RET_IP_); > > > > > > > > > > > > return __memmove(dest, src, len); > > > > > > > > > > > > > > > > > > Hi Dmitry, > > > > > > > > > > What do you think the following code is better than the above o= ne. > > > > > In memmmove/memset/memcpy, they need to determine whether size = < 0 is > > > > > true. we directly determine whether size is negative in memmove= and > > > > > return early. it avoid to generate repeated KASAN report. Is it= better? > > > > > > > > > > void *memmove(void *dest, const void *src, size_t len) > > > > > { > > > > > + if (long(size) < 0) { > > > > > + kasan_report_invalid_size(src, dest, len, _RET_= IP_); > > > > > + return; > > > > > + } > > > > > + > > > > > check_memory_region((unsigned long)src, len, false, _RE= T_IP_); > > > > > check_memory_region((unsigned long)dest, len, true, _RE= T_IP_); > > > > > > > > > > > > > > > check_memory_region() still has to check whether the size is ne= gative. > > > > > but memmove/memset/memcpy generate invalid size KASAN report wi= ll not be > > > > > there. > > > > > > > > > > > > If check_memory_region() will do the check, why do we need to > > > > duplicate it inside of memmove and all other range functions? > > > > > > > Yes, I know it has duplication, but if we don't have to determine s= ize<0 > > > in memmove, then all check_memory_region return false will do nothi= ng, > >=20 > > But they will produce a KASAN report, right? They are asked to check > > if 18446744073709551614 bytes are good. 18446744073709551614 bytes > > can't be good. > >=20 > >=20 > > > it includes other memory corruption behaviors, this is my original > > > concern. > > > > > > > I would do: > > > > > > > > void *memmove(void *dest, const void *src, size_t len) > > > > { > > > > if (check_memory_region((unsigned long)src, len, false, _= RET_IP_)) > > > > return; > > > if check_memory_region return TRUE is to do nothing, but it is no m= emory > > > corruption? Should it return early when check_memory_region return = a > > > FALSE? > >=20 > > Maybe. I just meant the overall idea: check_memory_region should > > detect that 18446744073709551614 bytes are bad, print an error, retur= n > > an indication that bytes were bad, memmove should return early if the > > range is bad. > >=20 > ok, i will send new patch. > Thanks for your review. >=20 how about this? commit fd64691026e7ccb8d2946d0804b0621ac177df38 Author: Walter Wu Date: Fri Sep 27 09:54:18 2019 +0800 kasan: detect invalid size in memory operation function =20 It is an undefined behavior to pass a negative value to memset()/memcpy()/memmove() , so need to be detected by KASAN. =20 KASAN report: =20 BUG: KASAN: invalid size 18446744073709551614 in kmalloc_memmove_invalid_size+0x70/0xa0 =20 CPU: 1 PID: 91 Comm: cat Not tainted 5.3.0-rc1ajb-00001-g31943bbc21ce-dirty #7 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x278 show_stack+0x14/0x20 dump_stack+0x108/0x15c print_address_description+0x64/0x368 __kasan_report+0x108/0x1a4 kasan_report+0xc/0x18 check_memory_region+0x15c/0x1b8 memmove+0x34/0x88 kmalloc_memmove_invalid_size+0x70/0xa0 =20 [1] https://bugzilla.kernel.org/show_bug.cgi?id=3D199341 =20 Signed-off-by: Walter Wu Reported-by: Dmitry Vyukov diff --git a/lib/test_kasan.c b/lib/test_kasan.c index b63b367a94e8..e4e517a51860 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -280,6 +280,23 @@ static noinline void __init kmalloc_oob_in_memset(void) kfree(ptr); } =20 +static noinline void __init kmalloc_memmove_invalid_size(void) +{ + char *ptr; + size_t size =3D 64; + + pr_info("invalid size in memmove\n"); + ptr =3D 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; @@ -734,6 +751,7 @@ 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 2277b82902d8..5fd377af7457 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; =20 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_); =20 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_); =20 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 =3D=3D 0)) return true; =20 + 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/report.c b/mm/kasan/report.c index 0e5f965f1882..0cd317ef30f5 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -68,11 +68,16 @@ __setup("kasan_multi_shot", kasan_set_multi_shot); =20 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); + } else { + 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)); + } } =20 static DEFINE_SPINLOCK(report_lock); 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 =3D=3D 0)) return true; =20 + if (unlikely((long)size < 0)) { + kasan_report(addr, size, write, ret_ip); + return false; + } + tag =3D get_tag((const void *)addr); =20 /*