From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=195.135.223.130 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793615768; b=IqkhAeaKOgX74wWB7Sd2VJA4UyttSRpAK+x9+Z2IiRKpBbMEbP8Vn2h6bUzKg7dA/mBK A+0ThFf5GZ2OO/bmWw4mUo/2qfSHyMS0Juv5fVaxYtEdGcP54jKalktqjFfbntQLm3REK Wbn1E5oycku3kEQbxmcI89b28hhMwoeV0eq8yEMbcMw9FNkDuygmfr9lStAvjKqOaw4nT oEF9fm+I4fnBp6yQUfFe6GA+Cq2a2rS/LZlepPswAUnDKc+T+ZczbiFq2i59lC0hJPKXV 8spJhycVxJh//RtAWBHPE0bmOBLi8HD/MUJRnMzi0JzSTouriM9Df0vv0qOsrouHt3w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793615768; h=DMARC-Filter:Received:DKIM-Signature:DKIM-Signature:DKIM-Signature: DKIM-Signature:Received:Received:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To: X-Spam-Flag:X-Spam-Level:X-Spamd-Result:X-Spam-Score; bh=TRhzeJj1YK8/7h9dIIOem89RRPtC49dqxALnXhljlDo=; b=lu5MjQsOXVvZkaGCU6MqqeXkNi24s3alBveGSKyooPmSQl7XQTP8b/WKpa+2YiA1+hSD PQyQu2HSmnAOpQNL61NBjm555rbqr/tSpUZ4UKsEKek4wFz74x7KdEXbFKG3YfqmrgkzN Rmb4SWvgZH5wkiXeSJumizEZOJk7uCynh7NhfkzvsO99w46jgnZTRDNQEjssDhoAaxo21 fJVyOKu/WNZF5zFEwdUAztBOV9DYI66xW6BBwQPQ4mFG/5y33xGD6ixto3t/e6rvMk6VQ OKgpPiLf2QYbc6RNanLVDLh7ZIX/8pPMqFScPy0jsBD4Hizv60/GLhPc38/E2RE3IzA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=suse.de; spf=pass smtp.mailfrom=suse.de; dkim=pass header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=n4K1m0W4; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b="cDqlMQ6/"; dkim=pass header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=n4K1m0W4; dkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b="cDqlMQ6/"; arc=none smtp.remote-ip=195.135.223.130 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EEBA6606A326 for ; Mon, 2 Nov 2026 10:36:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org EEBA6606A326 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=n4K1m0W4; dkim=pass header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=cDqlMQ6/; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.a=rsa-sha256 header.s=susede2_rsa header.b=n4K1m0W4; dkim=neutral header.d=suse.de header.i=@suse.de header.a=ed25519-sha256 header.s=susede2_ed25519 header.b=cDqlMQ6/ 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 154E121F64; Mon, 2 Nov 2026 10:36:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1793615766; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TRhzeJj1YK8/7h9dIIOem89RRPtC49dqxALnXhljlDo=; b=n4K1m0W4gEt+08pZ/ke7ocpeaWfykHo95r7XJVroWkyjbiT4hlZ8tSZkZ2CW8G+0uB/pcD Aso+EIUrHnHFdEysbLOTX6wVNdgNWeaoy4+l/tktODMKf5ksKAxcl7dTaQgfNTRiPn3agK MpkvITq2jcJNlb4zq4Kk8RL96nTyZNQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1793615766; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TRhzeJj1YK8/7h9dIIOem89RRPtC49dqxALnXhljlDo=; b=cDqlMQ6/px5ct/Lw6LJDpmI34aSvq3eKoIaCh8tYokTGUyPVgmMIL91f/zDsWFcoQRneaN BGawnmfF710E+uDA== Authentication-Results: smtp-out1.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1793615766; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TRhzeJj1YK8/7h9dIIOem89RRPtC49dqxALnXhljlDo=; b=n4K1m0W4gEt+08pZ/ke7ocpeaWfykHo95r7XJVroWkyjbiT4hlZ8tSZkZ2CW8G+0uB/pcD Aso+EIUrHnHFdEysbLOTX6wVNdgNWeaoy4+l/tktODMKf5ksKAxcl7dTaQgfNTRiPn3agK MpkvITq2jcJNlb4zq4Kk8RL96nTyZNQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1793615766; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TRhzeJj1YK8/7h9dIIOem89RRPtC49dqxALnXhljlDo=; b=cDqlMQ6/px5ct/Lw6LJDpmI34aSvq3eKoIaCh8tYokTGUyPVgmMIL91f/zDsWFcoQRneaN BGawnmfF710E+uDA== 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 22684134B8; Mon, 2 Nov 2026 10:36:05 +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 p7mnOJRn6GrtOwAAD6G6ig (envelope-from ); Mon, 02 Nov 2026 10:36:05 +0000 Date: Mon, 2 Nov 2026 10:36:03 +0000 From: Pedro Falcato To: "Lorenzo Stoakes (ARM)" Cc: Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , "Kiryl Shutsemau (Meta)" , "David Hildenbrand (Arm)" , Lance Yang , linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+10e72ea5747737bcd2ad@syzkaller.appspotmail.com, Songsen Yang Subject: Re: [PATCH] mm/vma: read anon_vma carefully in validate_mm() Message-ID: References: <20261102-fix-validate_mm-v1-1-5c309614ef15@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261102-fix-validate_mm-v1-1-5c309614ef15@kernel.org> X-Spam-Flag: NO X-Spam-Level: X-Spamd-Result: default: False [-11.80 / 50.00]; SUSE_INTERNAL_BYPASS(-9.00)[]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_TWELVE(0.00)[12]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TAGGED_RCPT(0.00)[10e72ea5747737bcd2ad]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[insta360.com:email,suse.de:email,imap1.dmz-prg2.suse.org:helo,appspotmail.com:email] X-Spam-Score: -11.80 On Mon, Nov 02, 2026 at 10:25:20AM +0000, Lorenzo Stoakes (ARM) wrote: > Commit 38564710f443 ("mm: implement and use vma_has_anon_rmap(), silence > KCSAN") rather clumsily converted the read of vma->anon_vma into a > vma_has_anon_rmap() without accounting for the separation between > assignment of anon_vma and later use of it. > > vma_has_anon_rmap() is intended as an optimistic check, so doesn't need to > protect against a torn read in vma->anon_vma. The caller is expected to > take care of this themselves if they then in fact access the field. > > validate_mm() does indeed then reference the field, so resolve the issue > via READ_ONCE(), and simplify the code by separating this into a new > function validate_mm_anon_rmap(). > > Finally, add a vma_assert_stabilised() to make it clear the required state > of the VMA. > > Fixes: 38564710f443 ("mm: implement and use vma_has_anon_rmap(), silence KCSAN") > Reported-by: syzbot+10e72ea5747737bcd2ad@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/6ae78418.6552420f.2a0efc.005c.GAE@google.com/ > Reported-by: Songsen Yang > Closes: https://lore.kernel.org/all/20261102074414.10902-1-yangsongsen@insta360.com/ > Signed-off-by: Lorenzo Stoakes (ARM) Reviewed-by: Pedro Falcato -- Pedro