From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7868B3E0C5C for ; Mon, 31 Aug 2026 10:06:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788170810; cv=none; b=leDzXUhQbMgACyitRJ+kXEg9n0tFbrFZ6xwUKe4ANEM/jR/0psY2DoAARlKeDXmuvWuQWO8WQu0HgbezgPlde5TCfzZc2CQvII/DOfJB23sKwtNsXXM1VNeP5L4yvJli+u3vk/5MldBpNeEnWQBKwPz3+pTVZhBg4bseOctgjBw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788170810; c=relaxed/simple; bh=n+da0A4rftMZVf5eI/Yp+jPaS4Rq6J2ReGW5L1G66o8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kznMPE7I43OVo6MIJeVSdW7xhFn7KF2uWhqTv2TTZVQIHyw8KWaR86BBPPxelwDgM8uyjJvGBPfHVhn2CaizwaKlsDzP4uZ1zG4JGTnMnEFFv6VxTW1NITzoBXDZZ2n06751GXucYIwmGGUJ93hb0ODZFSOplhj7So068dGmhTo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DATBspxv; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DATBspxv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14D741F000E9; Mon, 31 Aug 2026 10:06:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788170809; bh=rTCa3x1+NLElVZAzpXp0yBo3FBCgVkxgyOn4AqetuYc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=DATBspxvVs8agfsX5YhOCluh8TkwJHWyMCd4BSL1dTeYmEDfDsaCxZEJjDKrjKvOz +RF2NtLVrHEoSP3sc2RhlhoVs4Jo9HPzeIrhYcM8vAO2iDokd5nUHDsTlGtd5ePScf t76hAjtpxb7lZqcYvcun9GWkZpg+Ka+cC/yeXhBJUVRbpoVhrMnVuUuuBRXSbrnOT/ 4KqA0KoPyzsh+d5qhNIhDMGqzRXy5I6/qP6i2cWOUIoqEOb3O00cg2MbPu6go4uRut hSsH0kjGDEbsNwSnaemTYucOGQRHcltY6KgDJ0PUWzIMU0VmLUoZ07EEP1lOVeNagK fK9VMEfu6YK1g== Message-ID: <3d3c124b-04ae-49bf-8bbd-684b412f0a1c@kernel.org> Date: Mon, 31 Aug 2026 12:06:45 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/1] mm/slab_common: reject zero object_size before calculate_alignment Content-Language: en-US To: Longlong Xia , harry@kernel.org, akpm@linux-foundation.org Cc: hao.li@linux.dev, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Longlong Xia References: <20260826015506.3178758-1-xialonglong2025@163.com> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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 BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSNWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBrZXJuZWwub3JnPsLBsAQTAQoAWhYhBKlA1DSZLC6OmRA9UCJPp+fM gqZkBQJqFFy6GxSAAAAAAAQADm1hbnUyLDIuNSsxLjEyLDIsMgIbAwUJGtCBUAULCQgHAwUV CgkICwUWAgMBAAIeBQIXgAAKCRAiT6fnzIKmZJIUEADFx/tREzUImHrEwVHeSvDFmA7tJysI UVrlvrM09E7GIuzphzv7jYmo8n3ANpCczLEVr4G0syYQdTigaZgv3+FQDIIzhKih1IHhu1Ei XHlywNWKnQxxQEUNi5Mwx43wQz5XVw9F1A7gtKBKNtfogO511hAbrzagrYajyQacEJ/+sfhZ 9Da8ltHIXD8pcYaHUfQgEusCgmEd9+KrUwrTbckFKmYq5chuE6yJ4J0EmWknL096jIE6CnzF FRslQ3B1UKDjxVsm1ZHfir5NeWszLkTvGFsddFaWTgh8UycESG6VQzKXjjewXu2pG7YQYRpj QKm1W5X2TkwWkXRBZTmfmbhxIUMh3+zf5wQ463rSmDN/8v81tdqBtAW6rH/kzg1GvkaTHXn0 507yEHFzBksk2viAuIxxr7km8+/KARYLIdGtx30EG8cKzAUZOK6WqxtNCsXUJNrVE8CWrCaD icoNu7Fs1c5hmPHdSTnU48ce67449DdnO4neLSNhRiGlMHJgfJUmgrxu/hcYeOZ3haWmEQ2w uW1Mh01OHi8QZHCEyAbABrPs9GUgccc/4eYXX9hIgxfSkYzn8f+8NuIFPWl/0uTvjgqU29FQ SbzOLxHq9439Ox40G5mS5eZXRGxITYR+6TXvRGI6P/264jvflnr/pDGUttaikU+0W+1uxgKH cmYbEc7ATQRbGTU1AQgAn0H6UrFiWcovkh6EXVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQ La1PQDUi6j00ChlcR66g9/V0sPIcSutacPKfdKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMh FmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCTsTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sf bAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZOrIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq +aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahKtQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4n jQARAQABwsF8BBgBCgAmAhsMFiEEqUDUNJksLo6ZED1QIk+n58yCpmQFAmfIHFQFCRYU6J8A CgkQIk+n58yCpmS2PA//bqN1LfcotmArgElsa+0EGZSQlYgK48pm8WAeTXTngudP9IJ4SuKY HR5RNjHcBeqN+Me0zxRqYzRb8nGanHEkDyf4Im8DQM8d6vbyU+FcPmG4skud4kgS1zMHnlVd SXfSIwKC/hKgdHG8aBV7545Lz9X6Iohea+94wneD0aw/hqF+QWewGZhWJriWAZtvEkzNjQOi 4U9F/trLten/x7bpphDSnDMKJtITbtzATT1Dq7o7VpIUK1nCTQALMuMjKCdi8OdU/+V+R3O4 0PXWvX8qrvqYapVbZ+9KqT74FsuB0Ya9uXwgBF2Q6cRuETZk5vqaqKxzqoQZCO8AOz/58j6O 2RHNy/mZEN+7tJ5Tsq42zVJ4jxsT8b9YplavCMsnBgDeRWhcbYhCyttoL7nYISyWg4kQYZ/P wIV3OuNv2f8iKYsxNsRuClOAF82+gvqOy1/1pprFjy8uo2pkoOrb63aOP3vO5VHnRKgra6dq NcaZ+c6J4H+nEJGi2SkHAUJz5oBzuThvPudLvPA/SK8sKoM01IRxSihev/S/5WLazXB1PGem OCbvzC1IjWJJraxiDJ5IygokapUa2RP7+WBR22skQ3SSl6G107QgWKSyTOGWEaRmV53vxQLV jXuCmzSSasTL60zq5yGrT4/DYQVSNEUiUbG4pYekxJujNeEDkUlky0Y= In-Reply-To: <20260826015506.3178758-1-xialonglong2025@163.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/26/26 03:55, Longlong Xia wrote: > From: Longlong Xia > > calculate_alignment() with SLAB_HWCACHE_ALIGN halves ralign in a > while (size <= ralign / 2) loop. When size is 0, ralign eventually > reaches 0 and the condition stays true indefinitely, hanging the > kernel. > > kmem_cache_sanity_check() rejected size > KMALLOC_MAX_SIZE but not > size == 0. Add !size to the check so a 0-size kmem_cache_create() is > caught on CONFIG_DEBUG_VM builds, where it can be diagnosed when it > surfaces. > > Suggested-by: Hao Li > Assisted-by: Codex:gpt-5.6-sol > Signed-off-by: Longlong Xia Applied to mm/slab.git slab/for-next, thanks. I however support Harry's suggestion wrt (not) adressing theoretical issues like this going forward. > --- > Changes in v2: > - Drop the !object_size check in __kmem_cache_create_args() that v1 > added to the always-compiled path, and keep the guard only in the > debug-only kmem_cache_sanity_check(), as suggested by Hao Li. > > Link: https://lore.kernel.org/all/20260824092454.1693745-1-xialonglong2025@163.com/ > --- > mm/slab_common.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index 95ddbab290d4..e205a99d85cf 100644 > --- a/mm/slab_common.c > +++ b/mm/slab_common.c > @@ -102,7 +102,7 @@ static bool kmem_cache_is_duplicate_name(const char *name) > > static int kmem_cache_sanity_check(const char *name, unsigned int size) > { > - if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) { > + if (!name || in_interrupt() || !size || size > KMALLOC_MAX_SIZE) { > pr_err("kmem_cache_create(%s) integrity check failed\n", name); > return -EINVAL; > }