From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 520163E6383 for ; Mon, 20 Jul 2026 10:52:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784544739; cv=none; b=X6UPjd/fLHMuW3ug2+KQvbkrFT2l42iuRCUeoaruKJX2H0jx6ms8+w9/0Y/OBxJ3kMmTbPgMaCXEGjv09F5r7Tp4JS2nHwV9tAgjW+466/Nu1/zqrvrPQfzJTm4zW6L63qZXNG6Mtj3p4GIPP15ZaI1i6dqHA81nYMXS//Qnh/s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784544739; c=relaxed/simple; bh=eMgU/DzTgurbsrcSm/6o44Y82L9HhaSwXwlKctHa0uE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ORbZvCTsD28JbIsHH36E3It+7m4V1f0qL6+Y05PCerza/RVeUm+7xX890MByoVIHmZL5Sd+igF5HOzXaTx0GJLTisOBe7ot5qg/ifYSux70oxOeqyfE4cbBWGfv9U50ihtAiusnUkSbCjD0lEhm+Q8zdr+zgYIUSotd52aSr7wU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz; spf=pass smtp.mailfrom=suse.cz; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b=bIQvrJYY; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b=Ypjxl0pu; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b=bIQvrJYY; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b=Ypjxl0pu; arc=none smtp.client-ip=195.135.223.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.cz Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b="bIQvrJYY"; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b="Ypjxl0pu"; dkim=pass (1024-bit key) header.d=suse.cz header.i=@suse.cz header.b="bIQvrJYY"; dkim=permerror (0-bit key) header.d=suse.cz header.i=@suse.cz header.b="Ypjxl0pu" Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (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 558D779EEA; Mon, 20 Jul 2026 10:52:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1784544734; h=from:from:reply-to: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=DIFpln3chC5YRc1LC83Lur563AwKDo+8sTHThhbBFMQ=; b=bIQvrJYYRm417Wjm8+fVhR1zBkbcQBkjYBZw6pMpFOuySLId7tR2rPqYVpywcFL6/fZrXg 2d3+IClRK14c1QpBrEItdgAyHGrKSLE5zrgsUL+/m5S+m4Lt0LpRgbs/coKMg1SPZf+1Yu PNYGuH5/iEzL69qSwmv9V55L6Xef3lA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1784544734; h=from:from:reply-to: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=DIFpln3chC5YRc1LC83Lur563AwKDo+8sTHThhbBFMQ=; b=Ypjxl0puZuAV/8wQqZ9p0ib1C+9eJ5NxfBfDOdFClEGpo5sbQhifPRQRylkIWpwc20o9QV sueD0PcP90gdNKCw== Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=bIQvrJYY; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=Ypjxl0pu DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1784544734; h=from:from:reply-to: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=DIFpln3chC5YRc1LC83Lur563AwKDo+8sTHThhbBFMQ=; b=bIQvrJYYRm417Wjm8+fVhR1zBkbcQBkjYBZw6pMpFOuySLId7tR2rPqYVpywcFL6/fZrXg 2d3+IClRK14c1QpBrEItdgAyHGrKSLE5zrgsUL+/m5S+m4Lt0LpRgbs/coKMg1SPZf+1Yu PNYGuH5/iEzL69qSwmv9V55L6Xef3lA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1784544734; h=from:from:reply-to: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=DIFpln3chC5YRc1LC83Lur563AwKDo+8sTHThhbBFMQ=; b=Ypjxl0puZuAV/8wQqZ9p0ib1C+9eJ5NxfBfDOdFClEGpo5sbQhifPRQRylkIWpwc20o9QV sueD0PcP90gdNKCw== 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 483B1779AA; Mon, 20 Jul 2026 10:52:14 +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 JJhtEd79XWqQdgAAD6G6ig (envelope-from ); Mon, 20 Jul 2026 10:52:14 +0000 Date: Mon, 20 Jul 2026 12:52:05 +0200 From: David Sterba To: "Paul E. McKenney" Cc: Qu Wenruo , Boris Burkov , Chris Mason , David Sterba , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [BUG] fs/btrfs: KASAN "args" initialization gripe in btrfs_ioctl_get_csums() Message-ID: <20260720105205.GB10684@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <44261d8e-4361-4592-9fcf-b5c8d56220ba@paulmck-laptop> Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44261d8e-4361-4592-9fcf-b5c8d56220ba@paulmck-laptop> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) X-Rspamd-Action: no action X-Rspamd-Queue-Id: 558D779EEA X-Spam-Flag: NO X-Spam-Score: -4.21 X-Spam-Level: X-Spamd-Result: default: False [-4.21 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; HAS_REPLYTO(0.30)[dsterba@suse.cz]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmx.com]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.cz:+]; REPLYTO_DOM_NEQ_TO_DOM(0.00)[]; REPLYTO_ADDR_EQ_FROM(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[gmx.com,bur.io,fb.com,suse.com,vger.kernel.org]; RCVD_COUNT_TWO(0.00)[2]; RCPT_COUNT_SEVEN(0.00)[7]; DWL_DNSWL_BLOCKED(0.00)[suse.cz:dkim]; RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; DBL_BLOCKED_OPENRESOLVER(0.00)[twin.jikos.cz:mid,imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo,suse.cz:replyto,suse.cz:dkim] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org On Tue, Jul 14, 2026 at 03:38:43PM -0700, Paul E. McKenney wrote: > > > Fix (or at least suppress) this by initializing "args" to "{ 0 }". > > > > This is a little weird, as @args is immediately written with > > copy_from_user(). > > I was wondering about that myself. Perhaps it refuses to assume that > the entirety of args is overwritten? > > > So I'd say this may be specific to certain compiler version. > > Mind to provide the name and version of the compiler? > > gcc version 11.5.0 20240719 (Red Hat 11.5.0-14) (GCC) The 'maybe-uninitialized' warning occasionaly catches some arch and compiler combination that does not recognize the effects of initialization. The versions I see in fs/btrfs log are 10.2, loongarch64-gcc 12.3.1, gcc8 on m68k or mips, gcc 5 on ppc. Eventually reported when -Os is enabled.