From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D0716D3C546 for ; Wed, 10 Dec 2025 12:58:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0B0776B0006; Wed, 10 Dec 2025 07:58:08 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 039AF6B0007; Wed, 10 Dec 2025 07:58:07 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E1C516B0008; Wed, 10 Dec 2025 07:58:07 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id CC6326B0006 for ; Wed, 10 Dec 2025 07:58:07 -0500 (EST) Received: from smtpin29.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id D1B9613497B for ; Wed, 10 Dec 2025 12:58:06 +0000 (UTC) X-FDA: 84203564172.29.E800015 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) by imf08.hostedemail.com (Postfix) with ESMTP id 7B403160015 for ; Wed, 10 Dec 2025 12:58:04 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=eMcTYzlX; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=fPgis3gp; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=eMcTYzlX; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=fPgis3gp; dmarc=none; spf=pass (imf08.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.130 as permitted sender) smtp.mailfrom=vbabka@suse.cz ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1765371484; a=rsa-sha256; cv=none; b=KT20t3W+KQFgf14Vuk4mlOkP9fj0gUT2wAUIXQv5q6He2BJFSNiqzg2sza7mxvn/MWf9dg 9fCFXF1CxovEI/6+cvIN5vHgCMy2zx/vrAA0Q6JA6AtSFf9YEESCinYvAtQMz1DO6iq3Hl U0jx5C7BFU2Lesd0RsZk943pcezcQgk= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=eMcTYzlX; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=fPgis3gp; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=eMcTYzlX; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=fPgis3gp; dmarc=none; spf=pass (imf08.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.130 as permitted sender) smtp.mailfrom=vbabka@suse.cz ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1765371484; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0eetQyXD/sOvNibezct7Tv5ZQAuEm4ZVFaMv9Mjbh4E=; b=XPH2HmHYYOS08irVs5p+ee2rWqPPeCRKkm9R6sWrP0niRP0bkkaHxGJsqdXb8iOEh6MZIt ah/HRP4x8t0zjBakcNdCYrAY15TtyTsVZK9wNDJAiAi6IpSj0iES8qtKBBCGcwXVLeIZR7 TvLkxR2jlLlTg403UhMGhjhjn03WCgY= Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id B9B7E3388E; Wed, 10 Dec 2025 12:58:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1765371482; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=0eetQyXD/sOvNibezct7Tv5ZQAuEm4ZVFaMv9Mjbh4E=; b=eMcTYzlXpYLmLxRRqBffyjzH+cQV+HaQB10LMie7tRnMKZHe26vXpwRvUeSjZ5UBn0JNuU 8DgYNfljrx27Jy1r6/dX15zQuierbimxLnWSh1RfHgDFMg4t5uRYEzAJN/WRSD9OzX8b8J Yuw78+YifDTeGhMBfZL7lU0C4x2tL2Y= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1765371482; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=0eetQyXD/sOvNibezct7Tv5ZQAuEm4ZVFaMv9Mjbh4E=; b=fPgis3gprjFz7y6ob7fRcQ6zytoWvTnbIgZExBO6KmvgJ6mr9HtowMfVegHxogPoxJmDjU mDIn1tcxsximINBA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1765371482; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=0eetQyXD/sOvNibezct7Tv5ZQAuEm4ZVFaMv9Mjbh4E=; b=eMcTYzlXpYLmLxRRqBffyjzH+cQV+HaQB10LMie7tRnMKZHe26vXpwRvUeSjZ5UBn0JNuU 8DgYNfljrx27Jy1r6/dX15zQuierbimxLnWSh1RfHgDFMg4t5uRYEzAJN/WRSD9OzX8b8J Yuw78+YifDTeGhMBfZL7lU0C4x2tL2Y= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1765371482; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=0eetQyXD/sOvNibezct7Tv5ZQAuEm4ZVFaMv9Mjbh4E=; b=fPgis3gprjFz7y6ob7fRcQ6zytoWvTnbIgZExBO6KmvgJ6mr9HtowMfVegHxogPoxJmDjU mDIn1tcxsximINBA== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id A33433EA63; Wed, 10 Dec 2025 12:58:02 +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 IlKBJ1puOWkbEwAAD6G6ig (envelope-from ); Wed, 10 Dec 2025 12:58:02 +0000 Message-ID: Date: Wed, 10 Dec 2025 13:58:02 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/slub: reset KASAN tag in defer_free() before accessing freed memory Content-Language: en-US To: Deepanshu Kartikey , akpm@linux-foundation.org, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, harry.yoo@oracle.com, ast@kernel.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+7a25305a76d872abcfa1@syzkaller.appspotmail.com References: <20251210022024.3255826-1-kartikey406@gmail.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: <20251210022024.3255826-1-kartikey406@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 7B403160015 X-Rspamd-Server: rspam10 X-Stat-Signature: 3wb9ueabt387sp1x5idff4xi7pjw196k X-HE-Tag: 1765371484-232250 X-HE-Meta: U2FsdGVkX1+IShNAiJLzrGBwNqNU6KdDIEmikuuoGVztG1FrQQ4POE7SOgsg9Cxbdj8msEScZYu2cdYEL/tiUaUKt1yPM95rxE8oTQL1bjFsRmK8xCvgL1kmwGoM31UJ6a0Q3uiHGi+lKUAR/gWvGOZnuI1LGrBJB8y74eHd6vF11VORXeOC3LmcQUUvEqcsqscjGwcMb7eF8ZPlWB9zg/TRQZSydmI5Gm4d1bF6RC3BpZGyWgI+Slm85o3pM88jQl/ld7GgLkFMgsQl6BmoD+Xpz7+7JDo1dd826jRiiMb/v6OwSi7iTLP+UgY+AFkpwvoNdBW+r+gzgXl48h002EpvHUBlIVBSV2Xq8jGw4KHay3ZRaDypKT6W7ev027q0CCM36BqWBYMMf8jQJo22RPiylvrFEwZyWETAb5tniRTNShNis6S/ZHB8LG5nvKSzm7dgMMawdPdkX9zeyN4cmrVph0s+UQSpjSvgmJksdMeezJqi3WtT6WNXCziOKDQayN9UyLL7FxXa8kMGq4dpYQogASVg6kTCXR4cLZ/qERk4xNCLqk0mL7O5Os7ICkMlpXcyzwG0T8SRQPCGRFK2qEWosTCNWYvt7f0UtKPlzOiMxZZ2fxKRDSZPU8kdptM/UoxNTr3jbtZzYkvvbSTvsqBCNtllD/4H1WB6nZ6txENYQR0ehdxC5p4fVdofCSPBzpzmihAU+8Ty0ixuS9jSO0VnE65G+Cco96ebZYkPVOhVf7wh5XE/bDbOisIjGyQotjvYyM1SKv1vXaZeEFT90FoqqBqdpsUjwCW8hF3tkAYfBmZ0K6BfAMLLCpq4hFqnUh72OyyEqAfwD3oMYCt3e2KfzqgBLp42nv2fVWb/IMEH0z9pZ+8iji7O1zxBfx/q9TqoS59zQiEONfelVUcFlXB6BhTuA0yrD/uYUpU0bKnOrbUrALJ2RkO5OuaSLcDhbL3y2Rt1fKurZzCcgbj PPEC9BRM 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 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 12/10/25 03:20, Deepanshu Kartikey wrote: > When CONFIG_SLUB_TINY is enabled, kfree_nolock() calls kasan_slab_free() > before defer_free(). On ARM64 with MTE (Memory Tagging Extension), > kasan_slab_free() poisons the memory and changes the tag from the > original (e.g., 0xf3) to a poison tag (0xfe). > > When defer_free() then tries to write to the freed object to build the > deferred free list via llist_add(), the pointer still has the old tag, > causing a tag mismatch and triggering a KASAN use-after-free report: > > BUG: KASAN: slab-use-after-free in defer_free+0x3c/0xbc mm/slub.c:6537 > Write at addr f3f000000854f020 by task kworker/u8:6/983 > Pointer tag: [f3], memory tag: [fe] > > Fix this by calling kasan_reset_tag() before accessing the freed memory. > This is safe because defer_free() is part of the allocator itself and is > expected to manipulate freed memory for bookkeeping purposes. > > Fixes: af92793e52c3 ("slab: Introduce kmalloc_nolock() and kfree_nolock().") > Reported-by: syzbot+7a25305a76d872abcfa1@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=7a25305a76d872abcfa1 > Tested-by: syzbot+7a25305a76d872abcfa1@syzkaller.appspotmail.com > Signed-off-by: Deepanshu Kartikey Thanks, added cc: stable and pushed to slab/for-next-fixes > --- > mm/slub.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/slub.c b/mm/slub.c > index e6a330e24145..46959c6da2cf 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -6534,6 +6534,8 @@ static void defer_free(struct kmem_cache *s, void *head) > > guard(preempt)(); > > + head = kasan_reset_tag(head); > + > df = this_cpu_ptr(&defer_free_objects); > if (llist_add(head + s->offset, &df->objects)) > irq_work_queue(&df->work);