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Fri, 26 Sep 2025 12:48:14 +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 5eFoDI6L1mhjSwAAD6G6ig (envelope-from ); Fri, 26 Sep 2025 12:48:14 +0000 Message-ID: <96d00a94-1a4b-4378-8d89-0554f89778e1@suse.cz> Date: Fri, 26 Sep 2025 14:48:13 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH linux-next] alloc_tag: Fix boot failure due to NULL pointer dereference Content-Language: en-US To: ranxiaokai627@163.com, akpm@linux-foundation.org, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, harry.yoo@oracle.com, usamaarif642@gmail.com, surenb@google.com, shakeel.butt@linux.dev, hannes@cmpxchg.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, ran.xiaokai@zte.com.cn References: <20250926080659.741991-1-ranxiaokai627@163.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+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: <20250926080659.741991-1-ranxiaokai627@163.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 3FC18140007 X-Stat-Signature: jfjoz1jgbqhd9kuggas6w41edpr58ger X-HE-Tag: 1758890896-247768 X-HE-Meta: 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 gM6yQqI1 JMjGhUEFVTkXFeqL0Q5f5sDOahuPJB8Z541qFLjbbRYSdK2xDRBLBukBGsq8YiA4JolRNIgHPPkv2M9CqrjAiS+54NRx8kt1anu6gO8qvx40C62c2C515QAjkRarxhwCBgn85NiPWJsSL5D3YJirFS9ZiRxRaXavewVJvBkTMWq/TrUKOTwLFEy1jZ2bJoquF8xlmgCdYt6Vm8BbAWQu+CInyqAFyy+1TkPS3Jv2X+zgdJ5agdVDP/GjQzsGq6z57GVEJ1Ors7Tm0N8AYgBIvg6eNMjH00MWhzrWxM3O1iPma+KPJp7sHLydQYkbnKaLT7qZSAPiSO3soBLF76lM5rLkC64FutEgnbDSSpZax662Bk17zFqcEderEZTS+Y78GtFZD43wJgrPQYITiHsuyHVGlZb8T/FG7rc0n 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 9/26/25 10:06, ranxiaokai627@163.com wrote: > From: Ran Xiaokai > > There is a boot failure when both CONFIG_DEBUG_KMEMLEAK and > CONFIG_MEM_ALLOC_PROFILING are enabled. > > BUG: kernel NULL pointer dereference, address: 0000000000000000 > RIP: 0010:__alloc_tagging_slab_alloc_hook+0x181/0x2f0 > Call Trace: > kmem_cache_alloc_noprof+0x1c8/0x5c0 > __alloc_object+0x2f/0x290 > __create_object+0x22/0x80 > kmemleak_init+0x122/0x190 > mm_core_init+0xb6/0x160 > start_kernel+0x39f/0x920 > x86_64_start_reservations+0x18/0x30 > x86_64_start_kernel+0x104/0x120 > common_startup_64+0x12c/0x138 > > In kmemleak, mem_pool_alloc() directly calls kmem_cache_alloc_noprof(), > as a result, the alloc_tag structure associated with object_cache is not > defined neither initialized. So current->alloc_tag is NULL, > leading to a null pointer dereference. Agree with Harry. This should be enough: "as a result, current->alloc_tag is NULL, leading to a null pointer dereference." > Move the checks for SLAB_NO_OBJ_EXT, SLAB_NOLEAKTRACE, and > __GFP_NO_OBJ_EXT to the parent function __alloc_tagging_slab_alloc_hook() > to fix this. > > Also this distinguishes the SLAB_NOLEAKTRACE case between the actual memory > allocation failures case, make CODETAG_FLAG_INACCURATE more accurate. Good point. > Fixes: b9e2f58ffb84 ("alloc_tag: mark inaccurate allocation counters in /proc/allocinfo output") That's in mm-stable so the fix should go there (probably too late to fold now) if it's to be in the merge window PR. > Signed-off-by: Ran Xiaokai Acked-by: Vlastimil Babka > --- > mm/slub.c | 18 +++++++++--------- > 1 file changed, 9 insertions(+), 9 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 867a07260acf..09cbe580842c 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2197,15 +2197,6 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p) > { > struct slab *slab; > > - if (!p) > - return NULL; > - > - if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE)) > - return NULL; > - > - if (flags & __GFP_NO_OBJ_EXT) > - return NULL; > - > slab = virt_to_slab(p); > if (!slab_obj_exts(slab) && > alloc_slab_obj_exts(slab, s, flags, false)) { > @@ -2223,6 +2214,15 @@ __alloc_tagging_slab_alloc_hook(struct kmem_cache *s, void *object, gfp_t flags) > { > struct slabobj_ext *obj_exts; > > + if (!object) > + return; > + > + if (s->flags & (SLAB_NO_OBJ_EXT | SLAB_NOLEAKTRACE)) > + return; > + > + if (flags & __GFP_NO_OBJ_EXT) > + return; > + > obj_exts = prepare_slab_obj_exts_hook(s, flags, object); > /* > * Currently obj_exts is used only for allocation profiling.