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Wed, 23 Jul 2025 17:32:24 +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 eQWbK6gcgWhlZwAAD6G6ig (envelope-from ); Wed, 23 Jul 2025 17:32:24 +0000 Message-ID: <16c97e30-19c9-41e8-b73b-c0b3c8eceff3@suse.cz> Date: Wed, 23 Jul 2025 19:32:24 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [BUG] hard-to-hit mm_struct UAF due to insufficiently careful vma_refcount_put() wrt SLAB_TYPESAFE_BY_RCU Content-Language: en-US To: Jann Horn , Andrew Morton , "Liam R. Howlett" , Lorenzo Stoakes , Suren Baghdasaryan Cc: Pedro Falcato , Linux-MM , kernel list References: 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+fMgqZkBQJnyBr8BQka0IFQAAoJECJPp+fMgqZkqmMQ AIbGN95ptUMUvo6aAdhxaOCHXp1DfIBuIOK/zpx8ylY4pOwu3GRe4dQ8u4XS9gaZ96Gj4bC+ jwWcSmn+TjtKW3rH1dRKopvC07tSJIGGVyw7ieV/5cbFffA8NL0ILowzVg8w1ipnz1VTkWDr 2zcfslxJsJ6vhXw5/npcY0ldeC1E8f6UUoa4eyoskd70vO0wOAoGd02ZkJoox3F5ODM0kjHu Y97VLOa3GG66lh+ZEelVZEujHfKceCw9G3PMvEzyLFbXvSOigZQMdKzQ8D/OChwqig8wFBmV QCPS4yDdmZP3oeDHRjJ9jvMUKoYODiNKsl2F+xXwyRM2qoKRqFlhCn4usVd1+wmv9iLV8nPs 2Db1ZIa49fJet3Sk3PN4bV1rAPuWvtbuTBN39Q/6MgkLTYHb84HyFKw14Rqe5YorrBLbF3rl M51Dpf6Egu1yTJDHCTEwePWug4XI11FT8lK0LNnHNpbhTCYRjX73iWOnFraJNcURld1jL1nV r/LRD+/e2gNtSTPK0Qkon6HcOBZnxRoqtazTU6YQRmGlT0v+rukj/cn5sToYibWLn+RoV1CE Qj6tApOiHBkpEsCzHGu+iDQ1WT0Idtdynst738f/uCeCMkdRu4WMZjteQaqvARFwCy3P/jpK uvzMtves5HvZw33ZwOtMCgbpce00DaET4y/UzsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZ8gcVAUJFhTonwAKCRAiT6fnzIKmZLY8D/9uo3Ut9yi2YCuASWxr7QQZ lJCViArjymbxYB5NdOeC50/0gnhK4pgdHlE2MdwF6o34x7TPFGpjNFvycZqccSQPJ/gibwNA zx3q9vJT4Vw+YbiyS53iSBLXMweeVV1Jd9IjAoL+EqB0cbxoFXvnjkvP1foiiF5r73jCd4PR rD+GoX5BZ7AZmFYmuJYBm28STM2NA6LhT0X+2su16f/HtummENKcMwom0hNu3MBNPUOrujtW khQrWcJNAAsy4yMoJ2Lw51T/5X5Hc7jQ9da9fyqu+phqlVtn70qpPvgWy4HRhr25fCAEXZDp xG4RNmTm+pqorHOqhBkI7wA7P/nyPo7ZEc3L+ZkQ37u0nlOyrjbNUniPGxPxv1imVq8IyycG AN5FaFxtiELK22gvudghLJaDiRBhn8/AhXc642/Z/yIpizE2xG4KU4AXzb6C+o7LX/WmmsWP Ly6jamSg6tvrdo4/e87lUedEqCtrp2o1xpn5zongf6cQkaLZKQcBQnPmgHO5OG8+50u88D9I rywqgzTUhHFKKF6/9L/lYtrNcHU8Z6Y4Ju/MLUiNYkmtrGIMnkjKCiRqlRrZE/v5YFHbayRD dJKXobXTtCBYpLJM4ZYRpGZXne/FAtWNe4KbNJJqxMvrTOrnIatPj8NhBVI0RSJRsbilh6TE m6M14QORSWTLRg== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8E81A140014 X-Stat-Signature: oa4cxp4176s6nqd91hbq9zqpq5o3jc4q X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1753291946-46628 X-HE-Meta: U2FsdGVkX19ygUddCyMMD4juL8gNVOoOAosD07y5p0b5o9dMuIcxaMPPltFlsIS8dYecw5NjMkU+w8I1ed9tsprmeNBQsErQlIJZMfMXL/T/BOumSiJZrlmyu6T8mCvm8AMMmk7IKd3A95ayFxPaD/uHoGUosdgLQUJQV0kRvxbLGUIMezDb8mC9LmvbiFYMvtIT9UFtMrPIVG5ctSCbou78fuVz1i3XzLaZq2yOJwZDOv29JeT5PIQ98FgoqN2+EJnEmkqXqwqh3J0oXNxikw7MZa59459tfoNPiKpfNmtL+MnDZL87/qWPxfyMTeBkn0BXQysDxpzTzSMJbygRUOusE9rhrd1ZQF9zrXeKERAYlpd5jLinvpxkYGPGahmefffLTD6hnDKrZGAtWkWBWrCtuL0fZIPEKRCA07tFbO20fUR81rvgViAx6nVqJSHkBvBo5UG/1Ur4QIbR8+b5qWG3FlAKIP5PTku/5wyBK5i89gHFZ4KYlbUlkvxGB1OoxtLktuP30fkx7a2JVwxFZk02YD4VbqiD0u34aGzVfaipzXxqMFzs2hu/9QLLsSSuFQfY+dyZem7eOLEda5gTiRcBRZe90deoOXxn9365Cuj/TV93Ok5y5fdUxv7VwljcIXgCDqrgvjHt+h9hFKOlLyW39+3s3GthLYBiK0IpVlKlnWEhWqGKIwRy5tjc04OH+SmBDc07QXdcfdMxB3OIag8gEl4Wvn9vIsonCmZOx7rsuLouzD5pfRXcRG3RqGYve5EP3TzARDRSCp8lmwfQ9aV/mG19+3f98iD+YgxpJ47uM53NLEwdpUgblA3+PUxYls3mr4pDRfvAq2/qTev6oM/kynMRY9Fz45JrHEL7nkSmaG2cmaQTSJkmFILQ5R3Jm3c69IrWsEnDJx1KG4Fbbr2f13avHrmd6a5p5x/pND1BVM7KLvHobmmPqEi3LzHs6ZXe8CB9YrjUejeGm+w ksSpeasE rgIHlC29bnxjVXZkVxB0MycamJAFfJDaFu0jo+C1KDaRixpVTZUDo0LrCr/BdhmGubyPaT1Jd7f0aFa9pM/fsMkk3ceeJflfBDpCmoxoJsctRM4mLl+Ig362OwgNtg7b77RIxTE8YJuERjo9PPENM8Fjr7VZnR05HYVzWoY0iNzwNP8wHeTyqcE0YS1ydtUm5f+bNWWIau2L+Msvwf44tqgAViT+LTNkQGFRcoJqRu37zPu3iHIOd1c+ILGh1caXFgjonUlPZATReAyKbq2cHA58HUNfLFUa2ApTQjeuSzgD6Ag5QiWTc/TH3n3OolcaAWx3UXpgetfnqgJ4= 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 7/23/25 18:26, Jann Horn wrote: > There's a racy UAF in `vma_refcount_put()` when called on the > `lock_vma_under_rcu()` path because `SLAB_TYPESAFE_BY_RCU` is used > without sufficient protection against concurrent object reuse: Oof. > I'm not sure what the right fix is; I guess one approach would be to > have a special version of vma_refcount_put() for cases where the VMA > has been recycled by another MM that grabs an extra reference to the > MM? But then dropping a reference to the MM afterwards might be a bit > annoying and might require something like mmdrop_async()... Would we need mmdrop_async()? Isn't this the case for mmget_not_zero() and mmput_async()?