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Thu, 29 Aug 2024 07:49:32 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id vkkMBAwo0GYEUwAAD6G6ig (envelope-from ); Thu, 29 Aug 2024 07:49:32 +0000 Message-ID: <90df6237-f6bd-42b1-a755-659c5e76f527@suse.cz> Date: Thu, 29 Aug 2024 09:49:31 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2] mm, slub: avoid zeroing kmalloc redzone To: "Peng Fan (OSS)" , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Feng Tang , "open list:SLAB ALLOCATOR" , open list Cc: Peng Fan References: <20240829032911.2801669-1-peng.fan@oss.nxp.com> Content-Language: en-US From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: <20240829032911.2801669-1-peng.fan@oss.nxp.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 11688C0006 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: hx7es7p6gs1b3x4ufmyqzg3gknruo9iw X-HE-Tag: 1724917773-256331 X-HE-Meta: U2FsdGVkX18cfzKD0QUcogAQkyWWH+bAskiSJO7LK7jssEwoGc4ZoA4FARPwmhAkmiM3gM+MZuqY31gdPW3jcIyVildT2BhCkA3pqgzwS1azScVMhMZbJWZp3THP/OfzG66x5rVRuSqUnpR+aHOGa5Xn+cU82adryjxJYDe2Q8V/47swXUXT7sMhlOc6VmROFc1EW7Bx/fCH6rPR7CeQX+Ifj0nnIYiAGD61v+/gw+KAhLJ+11KgBnMg2tNRBhM48mFN808Mcq2wwqquH1DUyZzObXcwQQxJZt8PicdtBg33u7rbRSAdmb3tBFkfhBGF5TOLg5UAO3B167ussWGPI8XUDXzQBUQPYk7N1y91skcTDBlGEvzAEdhp6cX2TgJcqJnuLv6AHOUv43bYWs//VGw9mvumPUC0QnCCDWxNimA9XgUKK4qfpenpUgn0tItGC7O0rDYlVjZv3Jbr8O4Xjx8jenj6vsAlm2ztz562JD2DleKMeVvKsUonizZKc/Xz1MWEirEI3Ly4x0QXx/46F4BXUewsYVLcUZy7KAuha/D6Uq95ZWIyWB7HqbeemE05xo/++Wi7ExuR6n6wTXongmsjdo/aiYRtnis/SN6JB1YSOUR+Ec8Mp5W/fFdgxQlLMBCSyWK+DmJ07PgAdERuBZ+MbF1iExzoCSGf+SJAdEnRbA1yNmvN+CcCGljqrvyF6Sevn30YZMFeYb77CARBaE9lDr21LDai2Zk8wOKFZ8fOlBUsqJkKZFgpE15CesD4HNO9xEvqgApP3GQ6g/CWgpD9+9xgVo+ez8FjlrxHcN48JVlgiXiy5JGEcXGRmd9DQ1VmnOnlylq55cYtgo0mMRixQ+D8ms7MjTz1iabFQxIZD7IaR7gRDcIX+cb2m7lJuvcaQiMT6mWTgFhusRxtAzGVdh1NObRej1idAL8duysXO9GfQLx/RsBb/4q8Hk1HNdIAVwHbNprTDAOIpfa PzG8lfu0 DrmTLW7wXWbiVuIqfHOhdzGwgEVxl6mSRbua72EIB3R3SLJlUsDqfYbqUC0fDxogdnltS9jI8dBa0V4ICsSOVWI1J5/ZWc/ZXBPAHFAhRej6MNbBIsZYu+m9skfrjHeJCk8B9ceJ8JPxoTXvCddloBDfqruazrfKXKV7GINUlW5cBsLQFve2BHMLw4DfOW9OQYRCEhUMI33L2D5MwWgkCrQ+JJbz1VYlN9enmPx515cNqvIhsRN01UsmNIRditUU5j9Oag5f+qSs0TYAnWxrme0cBYjQ9bqFshDgJ4rkN8rTSXfJsKiWK/iG4wAQDcc1pkN82onsDfJM0xAlfmBKD97i1AwzpZyokAaAZgua1dce6Yg41O81K5DyKYBE7eVWNAAMrHAxLAgA6XWOyn+9NRB7l6yhH6Fkf+vPr 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: List-Subscribe: List-Unsubscribe: On 8/29/24 05:29, Peng Fan (OSS) wrote: > From: Peng Fan > > Since commit 946fa0dbf2d8 ("mm/slub: extend redzone check to extra > allocated kmalloc space than requested"), setting orig_size treats > the wasted space (object_size - orig_size) as a redzone. However with > init_on_free=1 we clear the full object->size, including the redzone. > > Additionally we clear the object metadata, including the stored orig_size, > making it zero, which makes check_object() treat the whole object as a > redzone. > > These issues lead to the following BUG report with "slub_debug=FUZ > init_on_free=1": > > [ 0.000000] ============================================================================= > [ 0.000000] BUG kmalloc-8 (Not tainted): kmalloc Redzone overwritten > [ 0.000000] ----------------------------------------------------------------------------- > [ 0.000000] > [ 0.000000] 0xffff000010032858-0xffff00001003285f @offset=2136. First byte 0x0 instead of 0xcc > [ 0.000000] FIX kmalloc-8: Restoring kmalloc Redzone 0xffff000010032858-0xffff00001003285f=0xcc > [ 0.000000] Slab 0xfffffdffc0400c80 objects=36 used=23 fp=0xffff000010032a18 flags=0x3fffe0000000200(workingset|node=0|zone=0|lastcpupid=0x1ffff) > [ 0.000000] Object 0xffff000010032858 @offset=2136 fp=0xffff0000100328c8 > [ 0.000000] > [ 0.000000] Redzone ffff000010032850: cc cc cc cc cc cc cc cc ........ > [ 0.000000] Object ffff000010032858: cc cc cc cc cc cc cc cc ........ > [ 0.000000] Redzone ffff000010032860: cc cc cc cc cc cc cc cc ........ > [ 0.000000] Padding ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 00 ............ > [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc3-next-20240814-00004-g61844c55c3f4 #144 > [ 0.000000] Hardware name: NXP i.MX95 19X19 board (DT) > [ 0.000000] Call trace: > [ 0.000000] dump_backtrace+0x90/0xe8 > [ 0.000000] show_stack+0x18/0x24 > [ 0.000000] dump_stack_lvl+0x74/0x8c > [ 0.000000] dump_stack+0x18/0x24 > [ 0.000000] print_trailer+0x150/0x218 > [ 0.000000] check_object+0xe4/0x454 > [ 0.000000] free_to_partial_list+0x2f8/0x5ec > > To address the issue, use orig_size to clear the used area. And restore > the value of orig_size after clear the remaining area. > > When CONFIG_SLUB_DEBUG not defined, (get_orig_size()' directly returns > s->object_size. So when using memset to init the area, the size can simply > be orig_size, as orig_size returns object_size when CONFIG_SLUB_DEBUG not > enabled. And orig_size can never be bigger than object_size. > > Fixes: 946fa0dbf2d8 ("mm/slub: extend redzone check to extra allocated kmalloc space than requested") > Reviewed-by: Feng Tang > Signed-off-by: Peng Fan Thanks, added to slab/for-next