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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 7 Apr 2020 12:05:36 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06avi18626390.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 037B4rYX44302654 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 7 Apr 2020 11:04:54 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 63B014C059; Tue, 7 Apr 2020 11:05:58 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 12E284C040; Tue, 7 Apr 2020 11:05:56 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.145.167.201]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 7 Apr 2020 11:05:55 +0000 (GMT) Subject: Re: [kernel-hardening] [PATCH 09/38] usercopy: Mark kmalloc caches as usercopy caches To: Vlastimil Babka , Jann Horn , Kees Cook Cc: Christoph Hellwig , Christopher Lameter , Jiri Slaby , Julian Wiedmann , Ursula Braun , Alexander Viro , kernel list , David Windsor , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Linux-MM , linux-xfs@vger.kernel.org, Linus Torvalds , Andy Lutomirski , "David S. Miller" , Laura Abbott , Mark Rutland , "Martin K. Petersen" , Paolo Bonzini , Christoffer Dall , Dave Kleikamp , Jan Kara , Luis de Bethencourt , Marc Zyngier , Rik van Riel , Matthew Garrett , linux-fsdevel , linux-arch , Network Development , Kernel Hardening , Michal Kubecek References: <201911121313.1097D6EE@keescook> <201911141327.4DE6510@keescook> <202001271519.AA6ADEACF0@keescook> <5861936c-1fe1-4c44-d012-26efa0c8b6e7@de.ibm.com> <202001281457.FA11CC313A@keescook> <6844ea47-8e0e-4fb7-d86f-68046995a749@de.ibm.com> <20200129170939.GA4277@infradead.org> <771c5511-c5ab-3dd1-d938-5dbc40396daa@de.ibm.com> <202001300945.7D465B5F5@keescook> <7d810f6d-8085-ea2f-7805-47ba3842dc50@suse.cz> From: Christian Borntraeger Autocrypt: addr=borntraeger@de.ibm.com; prefer-encrypt=mutual; keydata= xsFNBE6cPPgBEAC2VpALY0UJjGmgAmavkL/iAdqul2/F9ONz42K6NrwmT+SI9CylKHIX+fdf J34pLNJDmDVEdeb+brtpwC9JEZOLVE0nb+SR83CsAINJYKG3V1b3Kfs0hydseYKsBYqJTN2j CmUXDYq9J7uOyQQ7TNVoQejmpp5ifR4EzwIFfmYDekxRVZDJygD0wL/EzUr8Je3/j548NLyL 4Uhv6CIPf3TY3/aLVKXdxz/ntbLgMcfZsDoHgDk3lY3r1iwbWwEM2+eYRdSZaR4VD+JRD7p8 0FBadNwWnBce1fmQp3EklodGi5y7TNZ/CKdJ+jRPAAnw7SINhSd7PhJMruDAJaUlbYaIm23A +82g+IGe4z9tRGQ9TAflezVMhT5J3ccu6cpIjjvwDlbxucSmtVi5VtPAMTLmfjYp7VY2Tgr+ T92v7+V96jAfE3Zy2nq52e8RDdUo/F6faxcumdl+aLhhKLXgrozpoe2nL0Nyc2uqFjkjwXXI OBQiaqGeWtxeKJP+O8MIpjyGuHUGzvjNx5S/592TQO3phpT5IFWfMgbu4OreZ9yekDhf7Cvn /fkYsiLDz9W6Clihd/xlpm79+jlhm4E3xBPiQOPCZowmHjx57mXVAypOP2Eu+i2nyQrkapaY IdisDQfWPdNeHNOiPnPS3+GhVlPcqSJAIWnuO7Ofw1ZVOyg/jwARAQABzUNDaHJpc3RpYW4g Qm9ybnRyYWVnZXIgKDJuZCBJQk0gYWRkcmVzcykgPGJvcm50cmFlZ2VyQGxpbnV4LmlibS5j b20+wsF5BBMBAgAjBQJdP/hMAhsDBwsJCAcDAgEGFQgCCQoLBBYCAwECHgECF4AACgkQEXu8 gLWmHHy/pA/+JHjpEnd01A0CCyfVnb5fmcOlQ0LdmoKWLWPvU840q65HycCBFTt6V62cDljB kXFFxMNA4y/2wqU0H5/CiL963y3gWIiJsZa4ent+KrHl5GK1nIgbbesfJyA7JqlB0w/E/SuY NRQwIWOo/uEvOgXnk/7+rtvBzNaPGoGiiV1LZzeaxBVWrqLtmdi1iulW/0X/AlQPuF9dD1Px hx+0mPjZ8ClLpdSp5d0yfpwgHtM1B7KMuQPQZGFKMXXTUd3ceBUGGczsgIMipZWJukqMJiJj QIMH0IN7XYErEnhf0GCxJ3xAn/J7iFpPFv8sFZTvukntJXSUssONnwiKuld6ttUaFhSuSoQg OFYR5v7pOfinM0FcScPKTkrRsB5iUvpdthLq5qgwdQjmyINt3cb+5aSvBX2nNN135oGOtlb5 tf4dh00kUR8XFHRrFxXx4Dbaw4PKgV3QLIHKEENlqnthH5t0tahDygQPnSucuXbVQEcDZaL9 WgJqlRAAj0pG8M6JNU5+2ftTFXoTcoIUbb0KTOibaO9zHVeGegwAvPLLNlKHiHXcgLX1tkjC DrvE2Z0e2/4q7wgZgn1kbvz7ZHQZB76OM2mjkFu7QNHlRJ2VXJA8tMXyTgBX6kq1cYMmd/Hl OhFrAU3QO1SjCsXA2CDk9MM1471mYB3CTXQuKzXckJnxHkHOwU0ETpw8+AEQAJjyNXvMQdJN t07BIPDtbAQk15FfB0hKuyZVs+0lsjPKBZCamAAexNRk11eVGXK/YrqwjChkk60rt3q5i42u PpNMO9aS8cLPOfVft89Y654Qd3Rs1WRFIQq9xLjdLfHh0i0jMq5Ty+aiddSXpZ7oU6E+ud+X Czs3k5RAnOdW6eV3+v10sUjEGiFNZwzN9Udd6PfKET0J70qjnpY3NuWn5Sp1ZEn6lkq2Zm+G 9G3FlBRVClT30OWeiRHCYB6e6j1x1u/rSU4JiNYjPwSJA8EPKnt1s/Eeq37qXXvk+9DYiHdT PcOa3aNCSbIygD3jyjkg6EV9ZLHibE2R/PMMid9FrqhKh/cwcYn9FrT0FE48/2IBW5mfDpAd YvpawQlRz3XJr2rYZJwMUm1y+49+1ZmDclaF3s9dcz2JvuywNq78z/VsUfGz4Sbxy4ShpNpG REojRcz/xOK+FqNuBk+HoWKw6OxgRzfNleDvScVmbY6cQQZfGx/T7xlgZjl5Mu/2z+ofeoxb vWWM1YCJAT91GFvj29Wvm8OAPN/+SJj8LQazd9uGzVMTz6lFjVtH7YkeW/NZrP6znAwv5P1a DdQfiB5F63AX++NlTiyA+GD/ggfRl68LheSskOcxDwgI5TqmaKtX1/8RkrLpnzO3evzkfJb1 D5qh3wM1t7PZ+JWTluSX8W25ABEBAAHCwV8EGAECAAkFAk6cPPgCGwwACgkQEXu8gLWmHHz8 2w//VjRlX+tKF3szc0lQi4X0t+pf88uIsvR/a1GRZpppQbn1jgE44hgF559K6/yYemcvTR7r 6Xt7cjWGS4wfaR0+pkWV+2dbw8Xi4DI07/fN00NoVEpYUUnOnupBgychtVpxkGqsplJZQpng v6fauZtyEcUK3dLJH3TdVQDLbUcL4qZpzHbsuUnTWsmNmG4Vi0NsEt1xyd/Wuw+0kM/oFEH1 4BN6X9xZcG8GYUbVUd8+bmio8ao8m0tzo4pseDZFo4ncDmlFWU6hHnAVfkAs4tqA6/fl7RLN JuWBiOL/mP5B6HDQT9JsnaRdzqF73FnU2+WrZPjinHPLeE74istVgjbowvsgUqtzjPIG5pOj cAsKoR0M1womzJVRfYauWhYiW/KeECklci4TPBDNx7YhahSUlexfoftltJA8swRshNA/M90/ i9zDo9ySSZHwsGxG06ZOH5/MzG6HpLja7g8NTgA0TD5YaFm/oOnsQVsf2DeAGPS2xNirmknD jaqYefx7yQ7FJXXETd2uVURiDeNEFhVZWb5CiBJM5c6qQMhmkS4VyT7/+raaEGgkEKEgHOWf ZDP8BHfXtszHqI3Fo1F4IKFo/AP8GOFFxMRgbvlAs8z/+rEEaQYjxYJqj08raw6P4LFBqozr nS4h0HDFPrrp1C2EMVYIQrMokWvlFZbCpsdYbBI= Date: Tue, 7 Apr 2020 13:05:46 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <7d810f6d-8085-ea2f-7805-47ba3842dc50@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 20040711-0016-0000-0000-000002FFF93A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20040711-0017-0000-0000-00003363D38B Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.676 definitions=2020-04-07_03:2020-04-07,2020-04-07 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 spamscore=0 mlxscore=0 malwarescore=0 bulkscore=0 adultscore=0 phishscore=0 lowpriorityscore=0 clxscore=1015 suspectscore=0 mlxlogscore=907 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004070091 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 07.04.20 10:00, Vlastimil Babka wrote: > On 1/31/20 1:03 PM, Jann Horn wrote: > >> I think dma-kmalloc slabs should be handled the same way as normal >> kmalloc slabs. When a dma-kmalloc allocation is freshly created, it is >> just normal kernel memory - even if it might later be used for DMA -, >> and it should be perfectly fine to copy_from_user() into such >> allocations at that point, and to copy_to_user() out of them at the >> end. If you look at the places where such allocations are created, you >> can see things like kmemdup(), memcpy() and so on - all normal >> operations that shouldn't conceptually be different from usercopy in >> any relevant way. > > So, let's do that? > > ----8<---- > From d5190e4e871689a530da3c3fd327be45a88f006a Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka > Date: Tue, 7 Apr 2020 09:58:00 +0200 > Subject: [PATCH] usercopy: Mark dma-kmalloc caches as usercopy caches > > We have seen a "usercopy: Kernel memory overwrite attempt detected to SLUB > object 'dma-kmalloc-1 k' (offset 0, size 11)!" error on s390x, as IUCV uses > kmalloc() with __GFP_DMA because of memory address restrictions. > The issue has been discussed [2] and it has been noted that if all the kmalloc > caches are marked as usercopy, there's little reason not to mark dma-kmalloc > caches too. The 'dma' part merely means that __GFP_DMA is used to restrict > memory address range. > > As Jann Horn put it [3]: > > "I think dma-kmalloc slabs should be handled the same way as normal > kmalloc slabs. When a dma-kmalloc allocation is freshly created, it is > just normal kernel memory - even if it might later be used for DMA -, > and it should be perfectly fine to copy_from_user() into such > allocations at that point, and to copy_to_user() out of them at the > end. If you look at the places where such allocations are created, you > can see things like kmemdup(), memcpy() and so on - all normal > operations that shouldn't conceptually be different from usercopy in > any relevant way." > > Thus this patch marks the dma-kmalloc-* caches as usercopy. > > [1] https://bugzilla.suse.com/show_bug.cgi?id=1156053 > [2] https://lore.kernel.org/kernel-hardening/bfca96db-bbd0-d958-7732-76e36c667c68@suse.cz/ > [3] https://lore.kernel.org/kernel-hardening/CAG48ez1a4waGk9kB0WLaSbs4muSoK0AYAVk8=XYaKj4_+6e6Hg@mail.gmail.com/ > > Signed-off-by: Vlastimil Babka Acked-by: Christian Borntraeger > --- > mm/slab_common.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 5282f881d2f5..ae9486160594 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -1303,7 +1303,8 @@ void __init create_kmalloc_caches(slab_flags_t flags) > kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache( > kmalloc_info[i].name[KMALLOC_DMA], > kmalloc_info[i].size, > - SLAB_CACHE_DMA | flags, 0, 0); > + SLAB_CACHE_DMA | flags, 0, > + kmalloc_info[i].size); > } > } > #endif >