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Thu, 18 Jul 2024 10:30:33 +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 hZUTL8numGb0SwAAD6G6ig (envelope-from ); Thu, 18 Jul 2024 10:30:33 +0000 Message-ID: <65b7d88b-af4f-4869-9322-e38910abce6d@suse.cz> Date: Thu, 18 Jul 2024 12:30:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: list_lru: fix UAF for memory cgroup Content-Language: en-US To: Muchun Song , akpm@linux-foundation.org Cc: hannes@cmpxchg.org, muchun.song@linux.dev, nphamcs@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko References: <20240718083607.42068-1-songmuchun@bytedance.com> 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: <20240718083607.42068-1-songmuchun@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: EC23D100018 X-Stat-Signature: gtsbbhkhkmnqckc65ur4g1owgtmq77xb X-HE-Tag: 1721298635-342699 X-HE-Meta: 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 j90yxNOL eaX5yIX9CW1coGPXxslMEiRf1/QXPxSItNy2OASqNZZP6EeKy+3nOkxYz9k1RZN+HKk/ugWCCuPHMTcPgoUcQEewwsRi58Z73tJPTeM3axEZF4RF5/lDRsFSJh5/WH7raQhq3bL3RxODLUd7deOj/1ui1+9UicYtgU9SCpkPH8GwaU+9IOn1Q06HftnywYdAd1fRmkNx53/xBnN963M9aDqPsn+QfnOYdYCFtywsi4OrOdT9GsalEfylLToMWAHQSqIx2D4zOnE4eM3LViAlJs+3DT6BAR5ZF+taenIoJay/0Ks1yuXnIryLbkk9wHhXGSdKu5w7obiGqV/ihCbkCNd7zB2ujagnByI5nZRVG/SBJuiU= 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 7/18/24 10:36 AM, Muchun Song wrote: > The mem_cgroup_from_slab_obj() is supposed to be called under rcu > lock or cgroup_mutex or others which could prevent returned memcg > from being freed. Fix it by adding missing rcu read lock. Was the UAF ever observed, or is this due to code review? Should there be some lockdep_assert somwhere? > Fixes: 0a97c01cd20bb ("list_lru: allow explicit memcg and NUMA node selection) > Signed-off-by: Muchun Song > --- > mm/list_lru.c | 24 ++++++++++++++++++------ > 1 file changed, 18 insertions(+), 6 deletions(-) > > diff --git a/mm/list_lru.c b/mm/list_lru.c > index 3fd64736bc458..225da0778a3be 100644 > --- a/mm/list_lru.c > +++ b/mm/list_lru.c > @@ -85,6 +85,7 @@ list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx) > } > #endif /* CONFIG_MEMCG_KMEM */ > > +/* The caller must ensure the memcg lifetime. */ > bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid, > struct mem_cgroup *memcg) > { > @@ -109,14 +110,20 @@ EXPORT_SYMBOL_GPL(list_lru_add); > > bool list_lru_add_obj(struct list_lru *lru, struct list_head *item) > { > + bool ret; > int nid = page_to_nid(virt_to_page(item)); > - struct mem_cgroup *memcg = list_lru_memcg_aware(lru) ? > - mem_cgroup_from_slab_obj(item) : NULL; > + struct mem_cgroup *memcg; > > - return list_lru_add(lru, item, nid, memcg); > + rcu_read_lock(); > + memcg = list_lru_memcg_aware(lru) ? mem_cgroup_from_slab_obj(item) : NULL; > + ret = list_lru_add(lru, item, nid, memcg); > + rcu_read_unlock(); > + > + return ret; > } > EXPORT_SYMBOL_GPL(list_lru_add_obj); > > +/* The caller must ensure the memcg lifetime. */ > bool list_lru_del(struct list_lru *lru, struct list_head *item, int nid, > struct mem_cgroup *memcg) > { > @@ -139,11 +146,16 @@ EXPORT_SYMBOL_GPL(list_lru_del); > > bool list_lru_del_obj(struct list_lru *lru, struct list_head *item) > { > + bool ret; > int nid = page_to_nid(virt_to_page(item)); > - struct mem_cgroup *memcg = list_lru_memcg_aware(lru) ? > - mem_cgroup_from_slab_obj(item) : NULL; > + struct mem_cgroup *memcg; > > - return list_lru_del(lru, item, nid, memcg); > + rcu_read_lock(); > + memcg = list_lru_memcg_aware(lru) ? mem_cgroup_from_slab_obj(item) : NULL; > + ret = list_lru_del(lru, item, nid, memcg); > + rcu_read_unlock(); > + > + return ret; > } > EXPORT_SYMBOL_GPL(list_lru_del_obj); >