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Mon, 28 Jul 2025 08:52:22 +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 fE6bMUY6h2i8IgAAD6G6ig (envelope-from ); Mon, 28 Jul 2025 08:52:22 +0000 Message-ID: <431bf109-2bc7-4284-9b3a-7b36c329f25b@suse.cz> Date: Mon, 28 Jul 2025 10:52:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm: slub: avoid deref of free pointer in sanity checks if object is invalid Content-Language: en-US From: Vlastimil Babka To: Li Qiong , Christoph Lameter , David Rientjes , Andrew Morton , Matthew Wilcox Cc: Roman Gushchin , Harry Yoo , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20250725064919.1785537-1-liqiong@nfschina.com> <996a7622-219f-4e05-96ce-96bbc70068b0@suse.cz> 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: <996a7622-219f-4e05-96ce-96bbc70068b0@suse.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Queue-Id: 351D6140009 X-Stat-Signature: enmk8rn7wcno8oirn4xo4nqpo7mgbfy3 X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1753692744-94252 X-HE-Meta: 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 qJjs7z3c DybD0avA+8xu0En/D4BmMAY2zBJQjSIhmXvFJDO1JKKqOaWBLIFWwvk8QC5YztKIKl7eFe+l/Ifgka3CLunnXNbb22GDomDvHE+5d7VtIy5aX/26haQdscY+UkFtbCJXmlMsIpLBxVbjnpmtaEz3GxOVdoNw5Gvkxo2TaVkLkjDqlRQ2mSUGj8Oa6vv4vXyJa088jUzVYi6EcmeSDoe551qbWhSD2kcoMtqHCH2g2sASebWopl3J0MmUQ2dFJrfM9Xk7fGNjHCjVJ+5lVRvNgWBmfbwDaet5z13egLrHQtv/eB/6N4ZFKen+UmEvrAiCGKBZjqg7kYJGBwcY= 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 7/25/25 18:47, Vlastimil Babka wrote: > On 7/25/25 08:49, Li Qiong wrote: >> For debugging, object_err() prints free pointer of the object. >> However, if check_valid_pointer() returns false for a object, >> dereferncing `object + s->offset` can lead to a crash. Therefore, >> print the object's address in such cases. >> >> Fixes: bb192ed9aa71 ("mm/slub: Convert most struct page to struct slab by spatch") > > That was the last commit to change the line, but the problem existed before, > AFAICS all the time, so I did: > > Fixes: 7656c72b5a63 ("SLUB: add macros for scanning objects in a slab") > Cc: > >> Signed-off-by: Li Qiong > > Added to slab/for-next, thanks! Dropped based on Matthew's review >> --- >> v2: >> - rephrase the commit message, add comment for object_err(). >> --- >> mm/slub.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/mm/slub.c b/mm/slub.c >> index 31e11ef256f9..8b24f1cf3079 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -1097,6 +1097,10 @@ static void print_trailer(struct kmem_cache *s, struct slab *slab, u8 *p) >> size_from_object(s) - off); >> } >> >> +/* >> + * object - should be a valid object. >> + * check_valid_pointer(s, slab, object) should be true. >> + */ >> static void object_err(struct kmem_cache *s, struct slab *slab, >> u8 *object, const char *reason) >> { >> @@ -1587,7 +1591,7 @@ static inline int alloc_consistency_checks(struct kmem_cache *s, >> return 0; >> >> if (!check_valid_pointer(s, slab, object)) { >> - object_err(s, slab, object, "Freelist Pointer check fails"); >> + slab_err(s, slab, "Invalid object pointer 0x%p", object); >> return 0; >> } >> >